Dissertations / Theses on the topic 'Sheep and sheep breeding'

Breeding objectives were developed for Targhee sheep at different levels of prolificacy and triplet survival. Economic weights (EW) were derived for estimated breeding values (BV) from National Sheep Improvement Program genetic evaluations for 120 d weaning weight (WW), maternal milk (MM), yearling weight (YW), fleece weight (FW), fiber diameter (FD), staple length (SL), and prolificacy (PLC; lambs born/100 ewes lambing). A commercial flock was simulated, accounting for nonlinear relationships between performance and profit. Ewes were assumed mated to sires of specified BV and profit was derived from lifetime performance of lambs and replacement females from that lamb crop. Economic weights were determined as change in profit from use of sires with BV that were one additive standard deviation above the mean for each trait [1.98 kg for WW, 1.62 kg for MM, 2.90 kg for YW, 0..36 kg for FW, 0.99 microns for FD, 0.74 cm for SL, and 17.58 lambs/100 ewes for LC], while holding all other BV at breed average. Separate breeding objectives were derived for different ways of meeting increased nutrient needs (P = purchase hay, R = rent pasture, and L= limited flock size) and for different market lamb values (D = discounting lamb value for heavy weights, ND = no discount for heavy lambs). Based on replicated simulations, relative EW did not vary with prolificacy or triplet survival (P > 0.15) but were affected by feed costs and lamb market values (P < 0.01). Selection indexes were derived within and across simulated scenarios, and correlation (r) among indexes of > 0.90 indicated that an index could be used across multiple scenarios with little loss of selection efficiency. Indexes derived within feed cost scenarios (P, R, and L) and lamb value scenarios (D, ND) were strongly intercorrelated (r > 0.97). Correlations among average indexes for feed cost scenarios (0.97 for R and P, 0.70 for R and L; 0.85 for P and L) indicated that two feed cost scenarios could be used depending on whether winter forage was limited (L) or not (NL). The correlation between average indexes for these two scenarios was 0.78. Indexes were presented for combinations of feed cost and lamb value scenarios. Two indexes were suggested, representing the scenarios that apply to a large portion of Targhee producers. These indexes were for discounting heavy lambs with limited winter forage (D-L: 1.0 WW + 0.14 MM __ 0.76 YW + 1.22 FW __ 0.36 FD - 0.09 SL + 0.25 LC) and discounting heavy lambs with additional available forage (D-NL: 1.0 WW + 0.24 MM __ 0.34 YW + 1.65 FW __ 0.41 FD - 0.14 SL + 0.33 LC). For a standardized selection differential of one for the index, the expected changes in mean index value were $2.17 and $1.92 per ewe per generation for D-L and D-NL, respectively.
Master of Science

The study aims to determine the contribution made by available ram growth- and breed standard parameters on the sale price of auctioned rams in Namibia. These findings serve as an indication of the importance ram buyers place on individual parameters in selecting rams for breeding purposes. It furthermore tries to establish whether scientific measurement for the estimation of ram breeding values takes precedence over subjective appraisal. The analysis of the 100 day and 270 day growth performance of the progeny of selected Veldram tested rams were used to evaluate the accuracy of the estimation of ram breeding values and may serve to validate the proper execution of these Veldram tests.

The genetic outcome of operating an open nucleus system (ONS) in a population of 1200 sheep divided into individual flocks, was investigatd using simulation techniques, and a comparison to alternative breeding systems was made. Selection was for best linear unbiased prediction of breeding value (EBV) for a trait measurable on individuals before selection. Migration of animals between flocks was based on the EBV. The results of stochastic simulations indicated that, compared to selection within closed flocks (CF), the annual genetic gain could be increased by 25 to 40 per cent if an ONS was operated. The variation in selection response, and the rate of inbreeding were also lower. Simulation results showed that approximately 25 per cent of nucleus sires should be selected from the base flocks. Initial genetic differences between flocks had a short term effect on genetic gain in the ONS. Screening the population to ensure that the nucleus flock was initially composed of the best ewes, also only had a short term effect. The advantage of an ONS over CF selection was effected by flock size but not intitial heritability. The use of dispersed nucleus system and a sire referencing scheme with selection of sires across flocks, was investigated. The outcome of these systems was very similar to the ONS. The higher rate of genetic gain achieved in the ONS, compared to CF selection, was attributed to higher genetic selection differentials and maintenance of genetic variation within flocks. These effects were included in a deterministic model of the ONS. The model described the simulated data well, although changes in genetic variance at the outset of the ONS were underestimated. Failure to account for finite population effects in previous studies has resulted in underestimation of the benefits of an open nucleus system in small populations.

Genomic selection (GS) has been adopted by the dairy cattle breeding industry and the opportunity exists to implement this technology in UK beef and sheep breeding. However, these sectors do not appear so readily predisposed to GS implementation. Following an introduction to GS in Chapter 1, Chapter 2 investigated the structure of the little-studied UK beef breeding sector. This provided estimates of key commercial and pedigree population parameters, for use in modelling genetic gain from GS. Terminal traits were found to be the dominant selection goals, with 85% of beef-sired commercial matings resulting in progeny being slaughtered at a prime age. Pedigree bulls disseminated the majority of genes in the sector via natural service. The correlation between the terminal selection index (TI) and the sale price of breeding bulls was moderate, suggesting a modest uptake of genetic technology in the sector. Chapter 3 estimated selection intensity for TI, generation interval and the dissemination rate of improved genes in the pedigree Limousin population. In order to predict the genetic gain achievable in using GS in beef and sheep breeding, Chapters 4 to 6 undertook deterministic selection index simulations, incorporating genomic information as correlated traits. In Chapter 4, GS was modelled for terminal beef traits, when incorporating carcass information and accounting for likely genotype by environment interaction. Using a training population of 2000 sires, this concept was predicted to offer 40% greater genetic gain than existing BLUP selection using pedigree phenotypes. Gene flow methodology projected the commercial value of this gain to offer a substantial return net of genotyping costs. Chapter 5 explored GS for maternal beef traits within the concept of a nucleus breeding scheme. Whilst greater genetic gain was predicted with GS than with conventional BLUP, the economic value of this gain was projected to be too low to justify such a scheme in the UK. Chapter 6 proposed a synergy between computer tomography (CT) phenotypes and GS in sheep breeding. Developing a genomic predictor from male selection candidates with CT phenotypes and conventional performance records was predicted to increase genetic gain by 55% over BLUP selection without CT traits. Introducing GBV contributed most of the accuracy in this scenario, suggesting that the existing performance recording structure in UK sheep breeding could in the future be replaced by GS using CT. In the general discussion, the potential for GS in other beef and sheep traits was considered in the light of the outcomes of these simulations. Given the lack of vertical integration in UK beef and sheep sectors, the drivers for implementation of GS are examined. Finally, the options for international cooperation and the possibilities offered by future genotyping technology are considered. It was concluded that implementation of GS incorporating beef carcass phenotypes was merited and could provide a platform for future GS implementation in other novel traits. Sheep GS with CT traits was considered a higher risk strategy, due to the lack of evidence for uptake of existing EBV technology.

In seven experiments carried out under natural-daylength conditions at 57oN, Scottish Blackface and Border Leicester x Scottish Blackface ewes of varying physiological states and nutritional regimes received daily at 1500 h an oral dose of either melatonin dissolved in water and alcohol or the vehicle alone. Throughout the experiments blood samples were collected thrice weekly for progesterone, prolactin and follicle stimulating hormone concentrations (FSH) and at 10 to 15 minute intervals for periods of up to 24 h for luteinizing hormone (LH). Ovulation rates were determined by laparoscopy. When given from the beginning of June and mid-March respectively melatonin advanced and reversed the breeding season, the reversal being as effective in ewes with an extended lactation as in those weaned early or those that had not bred in the previous year. Short-term treatment (30 days) with melatonin during mid-anoestrus not only failed to advance the breeding season but delayed it. Longer term treatment (60 to 90 days) produced transient oestrous cyclicity with ewes returning to anoestrus within one month after the end of treatment. For ewes on a low plane of nutrition melatonin increased ovulation rate at first behavioural oestrus and appeared to reduce embryo mortality. In all experiments melatonin suppressed plasma prolactin 10 to 15 days after the start of treatment with levels remaining low throughout the period of treatment except during late pregnancy. There was no evidence that melatonin promoted a progressive increase in the frequency of the pulsatile release of LH or had any stimulatory effect on FSH secretion in the first 6 weeks of treatment. It did however increase plasma progesterone concentrations in the post-oestrus period.

Two experiments determined the effects of flaxseed supplementation on reproductive parameters in sheep. In experiment one, 240 multiparous Rambouillet ewes were assigned to one of two treatments: basal ration alone or basal ration with a Flaxlic® Sheep Tub offered over 35 days. Serum was collected weekly for progesterone (P4). Flaxseed supplementation did not improve progesterone concentration or reproductive parameters (P ≥ 0.26). In experiment two, 120 Rambouillet ram lambs were assigned to one of two treatments: basal ration alone or basal ration with a Flaxlic® Sheep Tub offered over 112 days. Scrotal circumference measurements, serum for testosterone, and semen were collected on day 84 and 112. Day effects were found for select semen measurements, testosterone, weight, and scrotal circumference (P ≤ 0.05). There was no effect of treatment on testosterone concentration (P = 0.99) or any semen quality characteristics (P ≥ 0.33). Overall, tub supplementation did not alter reproductive ability.

Breeding programmes that use elite sires with the best estimated breeding values for muscling traits have achieved significant improvement in lamb production in the UK. Further acceleration of the rate of genetic gain for the desirable production traits could be achieved using DNA marker-assisted selection (MAS) breeding strategies. The underlying causal genetic variants associated with improved muscling may be unknown and lying between a cluster of genes known as quantitative trait loci (QTL) or could be single nucleotide polymorphisms (SNP). LoinMAXTM, Texel muscling QTL (TM-QTL) and c.*1232G > A myostatin mutation were genetic variants that reported to be associated with improved muscling characteristics and hence subjected to further analysis in this project. It is essential before incorporating segregating genetic variants in any breeding scheme to comprehensively evaluate their effects on carcass traits. In-vivo scanning (ultrasound scanning (US) and computed tomography scanning (CT)), and carcass video image analyses (VIA) were used in the current studies. Objective VIAprediction weights of the carcass primal cuts could be the backbone of a value-based marketing system that is suggested to replace the current Meat and Livestock Commission (MLC) carcass grades for conformation scores (MLC-C) and fat class (MLC-F). The effect of a single copy of LoinMAXTM QTL (LM-QTL) compared to noncarriers was evaluated in UK crossbred lambs out of Scottish Mule ewes. M. longissimus lumborum (MLL) width, depth and area, as measured by CT scanning, were significantly greater in lambs heterozygous for LM-QTL compared to noncarriers. VIA detected a significant effect of the LM-QTL on the predicted weight of saleable meat yield in the loin primal cut (+2.2%; P < 0.05). The effects of the ovine c.*1232G > A myostatin mutation (MM), found on sheep chromosome 2, on carcass traits in heterozygous crossbred lambs sired by Texel and Poll Dorset rams were studied. Texel crossbred lambs carrying MM had increased loin depth and area. In both crossbred lambs, MM-carriers had significantly higher CT-estimated lean weight and proportion (2 to 4%) and muscle to bone ratios (by ~3%). Poll Dorset heterozygous crossbred animals had higher muscle to fat ratio (28%) and significantly lower fat-related measurements. The c.*1232G > A (MM) mutation as well as TM-QTL effects were evaluated in a different genetic background of Texel x Welsh Mountain crossbreed lambs. Carrying two copies of MM was associated with a significant positive effect on 8 week weight, a negative effect on ultrasound fat depth, a substantial decrease in MLC-fat score, positive impact on VIA-estimated weight of the hind leg, chump and loin primal cuts, as well as the muscularity of the hind leg and loin regions with greater loin muscle width, depth and area. Two copies of MM altered lambs‟ morphological traits with significantly wider carcasses across the shoulders, breast and hind legs and greater areas of the back view of the carcass when measured by VIA. TM-QTL significantly increased US-muscle depth and TM-QTL carriers had significantly greater loin muscle width and area measurements. Comparing TM-QTL genetic groups (homozygote allele carriers (TM/TM), heterozygote carriers of paternal and maternal origin of allele (TM/+ and +/TM, respectively) and homozygote non-carriers (+/+)) and TM-QTL mode of action were then studied. TM/TM carcasses were significantly heavier than non-carriers by 1.6 kg and scored higher conformation values when compared to heterozygote groups only. TM/+ lambs had significantly higher VIA-predicted weight and muscularity in the hind leg and loin, and higher loin dimensions relative to some other genotypic groups. The effect of TM-QTL on some carcass shape measurements was significant. TM-QTL mode of action results on the loin muscling traits supports the earlier reports of polar over dominance. In the light of growing calls to replace the current subjective carcass payment system with the objective VIA system that values the carcass according to the superiority of its cuts, I investigated the ability of US and CT measurements to predict the VIAestimated weights of the carcass primal cuts. Several prediction equations were examined but the best could be achieved when ultrasound measurement, CT linear measurements and live weight were fitted in the model. Since CT scanning information of elite sires is now being used for genetic selection for carcass merit, genetic parameters and genetic relationships between CT scanning measurements and post mortem traits (VIA and MLC-FC) were estimated. However, results were not sufficiently accurate to be of practical use due to lack of data.

PALA, AKIN. Effects of Three Twice-a-Year Breeding Schedules in Four Breeds of Sheep. (Under the direction of ODIS WAYNE ROBISON and ROGER LEE McCRAW).Straightbred populations of Dorset, Finnsheep, Composite I (50% Finnsheep, 25% Dorset, and 25% Rambouillet), and Composite II (50% Finnsheep, 25% Suffolk, and 25% Targhee) sheep were evaluated under three different twice-a-year breeding schedules. Ewes were exposed for 32 d starting on August 13 and February 5 for schedule I, on September 15 and March 10 for schedule II, and on October 22 and April 11 for schedule III. Approximately 100 ewes of each breed were exposed to rams during each breeding season. The experiment was conducted for five complete cycles starting with matings in the fall of 1984 and ending with matings in the spring of 1989. Data were obtained on 9419 lambs produced from 2334 ewes and 257 rams. Traits of primary interest were conception rate, litter size at birth, weaning weight, weaning weight adjusted for conception rate, litter weaning weight and litter weaning weight per ewe exposed. Lactation status had a significant effect on conception rate and litter size while number of lambs suckling did not have a significant effect on conception rate. Composite I ewes had the highest conception rates and litter size (P 0.10), both had larger litters (P < 0.01) than the other two breeds. Ewes giving birth in spring had the highest conception rate and heaviest lambs (P < 0.01). Animals bred in schedule I had the heaviest and largest litters, highest conception rate, heaviest lambs and highest litter weaning weight per ewe exposed (P < 0.01). Efficiency of twice-a-year lambing systems is greatly affected by breeds, breeding schedules and seasons. Twice-a-year lambing programs must use the correct breeding schedule. Further, using composite breeds can be of great benefit.Genetic parameters for conception rate, litter size at birth, weaning weight, weaning weight adjusted for conception rate, litter weaning weight and litter weaning weight per ewe exposed were estimated using REML with animal models. Heritability estimates for conception rate were adjusted to a normal scale. Standard errors of heritabilities for conception rate were calculated using three methods, including bootstrapping. Heritabilities were estimated overall and within breed. Estimates of heritability for conception rate ranged from 0.17 ± 0.01 (Dorset) to 0.27 ± 0.01 (Composite I). Heritability estimates for litter size were 0.08 ± 0.01, 0.19 ± 0.01, 0.14 ± 0.01 and 0.13 ± 0.01 for Dorset, Finnsheep, Composite I and Composite II, respectively. Heritabilities for litter weaning weight and litter weaning weight per ewe exposed were similar across breeds and ranged from 0.31 ± 0.01 to 0.36 ± 0.01. Heritability for weaning weight was higher for Dorset (0.65 ± 0.01) than for Composite I (0.57 ± 0.01). Finnsheep and Composite II had similar heritabilities (0.41 ± 0.01). Overall heritabilities for litter weaning weight, litter weaning weight per ewe exposed, weaning weight, weaning weight adjusted for conception rate, conception rate and litter size were 0.33 ± 0.02, 0.35 ± 0.01, 0.64 ± 0.01, 0.64 ± 0.01, 0.24 ± 0.01 and 0.16 ± 0.01, respectively. Overall Spearman rank-order correlations of litter weight traits with conception rate or litter size ranged from 0.81 to 0.88. Correlations within breed were generally high and positive. Genetic correlations between dry and lactating ewes for conception rate and litter size were small (0.009 and 0.108, respectively), indicating that rank of sires was inconsistent under different environments (lactation status). Selection should be practiced among lactating animals for conception rate and litter size in twice-a-year lambing systems.Heritability estimates were moderate to high for weight traits and low to moderate for reproduction traits, indicating that selection in twice-a-year lambing programs is feasible. There was no substantial evidence that heritabilities and rank correlations were different among the four breeds. Litter weaning weight may be increased along with conception rate and litter size in a selection program based on twice-a-year lambing. Small genetic correlation between dry and lactating ewes indicated that grouping sires according to the lactation status of the ewes is necessary in a selection program.

One of the main drivers influencing consumers in the purchasing of red meat is the level of visible fat, and this is particularly important in lamb, with lamb often being perceived as fatty. Consumer-driven preference for leaner meat, coupled with the meat processing industries preference for a reduction in carcass fat, increasing lean meat yield and reducing waste, have led to continued selection for lean growth and reduced fatness in several meat producing species The perception of lamb being fatty could be directly targeted in isolation by reducing overall fat levels, however there are related effects on meat (eating) quality, and the combined improvement and consistency of meat (eating) quality and the reduction of overall fatness is more complicated. It is apparent that fat content plays a significant role in meat (eating) quality. Generally four major fat depots are recognised in animal carcasses, these are: subcutaneous (under the skin); internal organ associated; intermuscular (between muscles and surrounding muscle groups); and intramuscular (marbling, between muscle fibres), the latter generally regarded as having the greatest association with meat (eating) quality. X-ray computed tomography (CT) can measure fat, muscle and bone in vivo in sheep and CT predictions of carcass composition have been used in commercial UK sheep breeding programmes over the last two decades. Together with ultrasound measures of fat and muscle depth in the loin region, CT measured carcass fat and muscle weights have contributed much to the success of breeding for leaner carcasses and increased lean meat yield. Recently it has also been considered that x-ray computed tomography provides the means to simultaneously estimate IMF and carcass fat in vivo. Thus the aim of this project is to investigate the use of two and three-dimensional x-ray computed tomography techniques in the estimation of meat (eating) quality traits in sheep, and to further investigate the genetic basis of these traits and the possibility of their inclusion into current breeding programmes. The primary approach was the use of two-dimensional x-ray computed tomography, determining the most accurate combination of variables to predict IMF and mechanical shear force in the loin. The prediction of mechanical shear force was poor with accuracies ranging from Adj R2 0.03 – 0.14, however the prediction of IMF in the loin was more promising. CT predicted carcass fat weight accounted for a moderate amount of variation in IMF (R2 =0.51). These accuracies were significantly improved upon by including other information from the CT scans (i.e. fat and muscle densities, Adj R2 >0.65). Average muscle density in a single or multiple scans accounted for a moderate amount of the variation in IMF (Adj R2 = 0.51-0.60), and again accuracies R2 >0.65 were achieved, independent of CT-measured fat areas or predicted fat weights. Similar results were achieved with the use of three-dimensional CT scanning techniques (Adj R2 0.51 – 0.71), however, there was a dramatically increased requirement for image analysis when compared to two-dimensional techniques, and the increase in accuracy was not significant. This suggests that the current method of two-dimensional image capture is sufficient in the estimation of IMF in vivo in sheep. The prediction equations developed as part of this work were applied across divergent breed types (Texel, Scottish Blackface and Texel cross mule), to investigate the transferability of the prediction equations directly across to other breeds of sheep. As part of this study, the IMF levels across the breed types and sexes were also compared and found that IMF was significantly affected by breed type (P<0.001) with Scottish Blackface lambs having higher levels of IMF when compared to Texel cross mule lambs, and the lowest levels of IMF were in the purebred Texel lambs at the same liveweight or similar levels of carcass fatness. Sex also had a significant effect on IMF across breeds (P<0.001) with females having higher levels of IMF at similar levels of both carcass fat and liveweight, and within breed, females had significantly higher levels of IMF in both the purebred Texel and Scottish Blackface lambs, when compared at similar levels of carcass fat and liveweight (P<0.05). Using the models previously developed in purebred Texel to predict IMF in the Scottish Blackface and Texel cross mule, accuracies were found to be R2 = 0.57 – 0.64 and R2 = 0.37 – 0.38 respectively. Providing evidence that the equations are transferable across to some breeds more successfully than others, however, given that there is currently no method of accurately estimating IMF in vivo, accuracies across to both breeds are acceptable. The genetic parameter estimation was unsuccessful using the same research-derived dataset as previously employed in the study. However the ambition was always to investigate the genetic relationships between traits in a large industry dataset, exploiting the wealth of commercial CT information available. These investigations were considerably more successful, and among the first to present genetic parameters of novel CT-derived IMF estimates. The results found moderate heritability estimates of h2 0.31 and 0.36 for the final selected prediction equations, with clear indications that one model not including CT predicted carcass fat or any other fat measures, was more independent of these measures and the two separate prediction methods were highly genetically correlated with each other (rg = 0.89). The results from this study show that not only is it possible to accurately estimate IMF levels in the loin of Texel sheep using CT scanning, but that, until breed specific predictions are developed, the methods developed in this study are transferable across some breed types. The results also show that CT predicted IMF is heritable, independent of overall fatness and has the potential to be included in current breeding programmes. These findings can now be used to develop breeding programmes which enable breeders to make the best use of CT scanning technology to improve carcass composition while maintaining or possibly improving aspects of meat (eating) quality.

Genotype by environment interactions (GxE) can form a potential source of inefficiency in animal breeding if selection decisions are made without accounting for their effects. The UK sheep industry covers an assorted range of farming systems and environments, with each flock having a unique and diverse set of resources and management styles. As a result, what may be the best performing genotype in one environment may not necessarily be the best performing genotype in another. This thesis reports on an investigation into the presence of GxE within the UK sheep industry. Pedigree and performance data, available from both hill and terminal sire breeds, were analysed using a number of different methods. When environments were defined as 2 individual hill farms, genetic correlations were estimated between farms, for a range of Scottish Blackface ewe and lamb traits. Those found to be significantly different from 1 (P<0.05), and therefore indicating the presence of GxE, were lamb birth weight and ewe premating weight. Following on from this, fine-scale information obtained by a farmer questionnaire, from 79 different terminal sire flocks was combined with nationally-available climatic data and analysed using principle coordinate analysis and non-hierarchical clustering methods. Three distinct clusters of farm environments were identified, with grazing type, climatic conditions and the use of vitamin/mineral supplements proving to be the most distinguishing factors. The presence of GxE was then investigated by estimating genetic correlations between the clusters identified, using performance data from Charollais lambs, for 21 week old weight (21WT), ultrasound back-fat (UFD) and muscle (UMD) depths. The correlations estimated between clusters 1 and 2, which had the highest number of common Charollais sires used, were all low and significantly different from 1 (P<0.05) suggesting GxE was evident in terms of both scaling and re-ranking. Finally, the relationship between the level of concentrate feed used in each flock, as obtained from the questionnaire, and performance and climatic information available nationally for all flocks was estimated using canonical correlation analysis. This allowed the development of a farm environment scale, applicable to all flocks within the UK, and the use of reaction norm analyses to investigate the presence of GxE. The reaction norm describes the phenotype of an individual animal as a function of the environment. The environment scale developed, using data from Texel flocks only, went from low performance averages and poorer weather conditions to high performance averages and improved weather conditions. The slope of the reaction norm measures the sensitivity of an animal to a change in the environment. For each trait, (21WT, UMD and UFD), evidence of both re-ranking and scaling of sires were observed. A number of “robust” sires, with a low level of environmental sensitivity, were also identified. The findings from these analyses may have implications for future sheep breeding programmes. Providing a suitable “measure of environment” can be agreed, the identification of sires that perform well in specific environments, as well as those who perform consistently across a number of different environments, would be beneficial for farmers. This would potentially remove any unwanted effects of GxE and allow the farmer to select animals best suited to their overall farm environment.

The South African sheep industry has experienced an increase in the price of meat and wool over the past several years. This has led to an interest in intensification of sheep production off planted pastures. Due to this phenomenon an economic viability study was done on the intensification of sheep production on cultivated pastures under irrigation. When intensifying sheep production, certain management practices need to be incorporated in order to enhance the output obtained per hectare and to overcome the higher input cost of production. Management practices that could be included are creep feeding, accelerated breeding and feedlotting of lambs after weaning. In order to determine the economic viability of such a system, certain production parameters need to be obtained for producing sheep intensively from cultivated pastures. Three studies were conducted to obtain the required production parameters; these were then followed by an economic evaluation incorporating the parameters obtained from the studies. All the studies were conducted at Kromme Rhee and Langgewens, two research farms of the Department of Agriculture in the Western Cape.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: Fluctuations and a general decline in the ratio between wool and meat prices resulted in marked changes in the South African sheep industry. Commercial producers now exploit other mechanisms such as terminal crossbreeding of Merino-type with meat type breeds or dual-purpose breeds to attain short-term benefits resulting from price fluctuations between wool and mutton without compromising the wool-producing capacities of ewe flocks. Most components of lamb production have low heritability. However, heterosis can be achieved by mating wool-type breeds with specialist meat breed rams. Genetic improvement of livestock depends on defining breeding objectives, estimation of genetic parameters and accurately identifying the right animals to be used for future breeding. Genetic parameters for traits of economic importance in terminal sire sheep breeds that could be used on Merino-type ewes in commercial operations in South Africa had not been published for the national flock apart from a preliminary study having been conducted by Olivier et al. (2004). Selection objectives were poorly defined due to lack of parameter estimates for variance and covariance components. Against this background, this study obtained pedigree information and live weight data from the National Small Stock Improvement Scheme for the Dormer, Ile de France and Merino Landsheep and estimated non-genetic factors and genetic parameters influencing early growth traits. Genetic and phenotypic trends for early growth traits were constructed for the three breeds to monitor genetic progress. Non-genetic factors influencing early growth traits in the Dormer, Ile de France and Merino Landsheep were estimated using data obtained from the National Small Stock Improvement Scheme of South Africa. The original data sets for the Dormer, Ile de France and Merino Landsheep consisted of the following number of records respectively: 52 202, 35 553 and 7 772. However, pre-weaning weights were available for the Ile de France and Merino Landsheep breeds only and post-weaning weights were available only for the Dormer breed. The data sets were complicated to such an extent that smaller data sets had to be generated to analyse for fixed effects. The traits that were analysed were birth weight, pre-weaning weight, weaning weight and post-weaning weight. The fixed effects, identified as having a significant effect (P < 0.01) on early growth traits were sex of lamb, birth type, age of dam, contemporary groups, age at which the trait was recorded and month of birth and year of birth in the Merino Landsheep breed. Although some significant interactions were found, they were subsequently ignored owing to their very small effects. In all three breeds, male lambs were significantly (P < 0.001) heavier than female lambs and single-borne lambs were significantly heavier at birth than multiple borne lambs. The age of dam had a significant curvilinear regression on all early growth traits in all three terminal sire sheep breeds. It was concluded from the study that the influence of non-genetic factors on early growth traits should be adjusted for or eliminated statistically in genetic evaluations to get accurate genetic parameter estimations. (Co)variance estimates for birth weight, weaning weight and post-weaning weight were obtained for the Dormer breed using restricted maximum likelihood procedures (REML). Direct heritabilities (h2) in single-trait analyses were 0.21 ± 0.03, 0.23 ± 0.02 and 0.29 ± 0.05 for birth weight, weaning weight and post-weaning weight, respectively. Direct heritabilities of 0.28 ± 0.04, 0.55 ± 0.06 and 0.32 ± 0.02 for birth weight, weaning weight and post-weaning weight respectively were obtained using three-trait analysis. Direct maternal genetic effects (m2) were excluded from the analyses because of the failure to partition maternal effects into maternal genetic and maternal permanent environmental effects (m2 and c2). This culminated as a consequence of poor data and population structures emanating from the loss of genetic links across flocks due to the random entrance and exit of flocks from the recording scheme. Maternal permanent environment was estimated at 0.15 ± 0.02, 0.13 ± 0.02 and 0.20 ± 0.03 for birth weight, weaning weight and post-weaning weight respectively using single-trait analysis. The correlation between direct effects and maternal effects (ram) was excluded from the analyses due the structure of the data. Genetic, phenotypic and environmental correlations between early growth traits were low to moderate. The medium to high heritability estimates for early growth traits obtained in the study led to the conclusion that Dormer sheep can successfully be used in terminal crossbreeding programs to improve meat production characteristics. Direct heritability estimates were 0.31 ± 0.14, 0.09 ± 0.02 and 0.14 ± 0.003 for birth weight, pre-weaning weight and weaning weight respectively using single-trait analysis for the Ile de France breed. Maternal effects were significant for all the traits studied despite the failure to properly partition them into their components due to the loss of genetic linkages across generations emanating from poor data structure. Genetic, phenotypic and environmental correlations were estimated using three-trait analysis and were found to be low to moderate for early growth traits. Direct genetic and maternal permanent environmental ratios were also computed and they did not differ much from the results obtained using single-trait analyses. The reasonable genetic parameter estimates obtained in the study led to the conclusion that the Ile de France can be selected to use as sires in crossbreeding programs. Genetic parameters were estimated for early growth traits in the Merino Landsheep breed. REML estimates of birth weight, pre-weaning weight and weaning weight were obtained using animal models in single-trait analyses. The direct heritability estimate for birth weight was 0.23 ± 0.13 using an animal model with additive direct genetic effects and dam permanent environmental effects as the only random factors. The dam permanent environmental effect for birth weight amounted to 0.10 ± 0.07. Direct heritability for pre-weaning weight was 0.36 ± 0.05 and the dam permanent environmental effect 0.56 ± 0.03. Weaning weight was estimated using an animal model that contained direct additive effects and dam permanent environmental effects. The direct heritability estimate for weaning weight was 0.17 ± 0.03. Maternal genetic effects were estimated to be 0.02 ± 0.01. Genetic and phenotypic trends were constructed for early growth traits in the Dormer, Ile de France and Merino Landsheep breeds. The traits that were considered were birth weight, pre-weaning weight, weaning weight and post-weaning weight. However, pre-weaning weights were available for the Ile de France and Merino Landsheep breeds only and post-weaning weights were available only for the Dormer breed. The Dormer exhibited significant improvement in the phenotypic and genetic aspects of early growth traits during the 17 years of evaluation (1990-2007). The average predicted direct breeding values of birth weight decreased by 0.055 % during the evaluation period. The predicted direct breeding value for weaning weight increased by 0.12 % during the 17 year period. Post-weaning weight improved by 0.32 % per annum. The Ile de France registered an increase in the predicted breeding value of birth weight which amounted to 0.025 % per annum. Averaged direct breeding values for pre-weaning weight increased at an annual rate of 0.23 %. and that of weaning weight increased by 1.21 %. In the Merino Landsheep the predicted direct breeding value for birth weights decreased by 0.04 % per annum and pre-weaning and weaning weights increased by 0.36 % and 0.10 % respectively. The trends were obviously biased due to inconsistencies in data structure and very few records available for analysis in this breed. In conclusion, it was evident that the additive genetic variation was available for all the early growth traits in all the three breeds. Although adequate genetic variation for substantial genetic progress was available, only modest rates of progress were attained for all the traits in all three breeds. The only possible exception was weaning weight in the Ile de France breed, which improved at > 1 % per annum. At least all changes were in the desired direction. Breeders should be encouraged to record data consistently, as one of the major shortcomings in the data for all breeds were a lack of continuity in the submission of data to the NSIS. More informative analyses ought to be feasible if this requisite could be met.
AFRIKAANSE OPSOMMING: Die wisselende en algemene afname in die prysverhouding van wol tot vleis het merkbare veranderinge in die Suid-Afrikaanse skaapbedryf teweeggebring. Kommersïele produsente maak nou gebruik van ander metodes soos terminale kruisteling van Merino-tipe ooie met vleis tipe vaars of dubbel-doel rasse om korttermynvoordele uit die wisselende wol en vleis pryse te behaal, sonder om die wol-produksie potensiaal van die ooi-kudde te benadeel. Die meeste van die lamproduksie eienskappe het ‘n lae oorerflikheid. Nietemin, kan heterose wel behaal word deur die kruisteling van wol-tipe rasse met spesialis vleisramme. Genetiese verbetering van vee is afhanklik van die beskrywing van die teeltdoelwitte, die akkurate beraming van genetiese parameters en die noukeurige identifikasie van die geskikste diere vir toekomstige teling. Genetiese parameters vir ekonomies belangrike eienskappe van terminale ramrasse wat gebruik kan word op Merino-tipe ooie in die kommersiële skaapbedryf in Suid-Afrika is nog nie gepubliseer vir die nasionale kudde nie, behalwe vir ‘n voorlopige studie wat gedoen is deur Olivier et al. (2004). Seleksiedoelwitte is nie duidelik beskryf nie a.g.v ‘n tekort aan akkurate parameterberamings vir (ko)variansie komponente. Hierdie studie het dus stamboominligting en lewende gewig data verkry vanaf die Nasionele Kleinveeverbeteringsskema vir die Dormer-, Ile de France- en die Merino landskaaprasse en nie-genetiese faktore sowel genetiese parameters vir vroeë lamgewigte beraam. Genetiese en fenotipiese tendense vir vroeë lamgewigte is vervolgens opgestel vir drie rasse om genetiese vordering te evalueer. Die oorspronklike datastelle vir die Dormer, Ile de France en die Merino Landskaap het uit die volgende aantal rekords bestaan, onderskeidelik: 52 202, 35 553 en 7 772. Voor-speen gewigte was net beskikbaar vir die Ile de France- en die Merino Landskaaprasse, en na-speen gewigte was net beskikbaar vir die Dormerras. Die beperkings in die datastelle het genoodsaak dat dat kleiner datastelle ontwikkel moes word om die vaste effekte te analiseer. Die eienskappe wat ge-analiseer was, was geboortegewig, voor-speengewig, speengewig en naspeengewig. Die vaste effekte wat vroeë lamgewigte betekenisvol (P < 0.01) beïnvloed het, was geslag van die lam, geboortestatus, ouderdom van die ooi, kontemporêre groep, die ouderdom waarop die eienskap aangeteken is en (in sommige gevalle) die maand en jaar van geboorte. Alhoewel daar sommige betekenisvolle interaksies was, is dit nie in die finale modelle ingesluit nie, omdat dit min tot die verklaarde variasie bygedra het. In al die rasse het ramlammers swaarder (P < 0.001) geweeg as ooilammers. Enkelinge was ook swaarder (P<0.001) as meerlinge. Die ouderdom van die moer van die lam het ‘n beduidende kromlynige invloed op alle vroeë lamgewigte by al drie terminale ramrasse gehad. Die gevolgtrekking van hierdie studie is dat die invloed van nie-genetiese faktore op vroeë lamgewigte in ag geneem moet word, of dat dit moet statisies elimineer word in die genetiese evaluasie om akkurate genetiese beramings te verkry. (Ko)variansie beramings vir geboortegewig, speengewig en na-speengewig is deur gebruik te maak van die “restricted maximum likelihood procedures” (REML) vir die Dormerras verkry. Die direkte oorerflikheid (h2) wat verkry was deur die mees geskikste diere model in ‘n enkel-eienskap analise te gebruik was onderskeidelik 0.21 ±0.02, 0.23 ±0.02 en 0.29± 0.05 vir geboortegewig, speengewig en na-speengewig. Direkte ooreenstemende oorerflikheid wat uit die drie-eienskap analise was 0.28±0.04, 0.55±0.06 en 0.32±0.02 onderskeidelik vir geboortegewig, speengewig en na-speengewig. Direkte maternale genetiese effekte (m2) is uitgesluit vanaf die analise weens die onvermoë om die maternale effekte te verdeel in maternale genetiese effekte en maternale permanente omgewings effekte (m2 en c2). Dit was a.g.v onvolledige data en populasiestrukture wat gelei het tot die gebrek in genetiese bande oor kuddes, wat ontstaan het weens kuddes wat slegs tydelik data tot die skema bygedra het. Maternale permanente omgewingeffekte is geskat op onderskeidelik 0.15±0.02, 0.13±0.02 en 0.20±0.03 vir geboortegewig, speengewig en na-speengewig met die gebruik van die enkel-eienskap analise. Die korrelasie tussen direkte effekte en maternale effekte (ram) is uitgesluit a.g.v die gebrekkige struktuur van die data. Genetiese-, fenotipiese- en omgewingskorrelasies tussen die vroeë lamgewigte was laag tot matig. Die matige tot hoë oorerflikheidberamings vir vroeë lamgewigte uit hierdie studie het gelei tot die gevolgtrekking dat Dormer skape suksesvol gebruik kan word in terminale kruisteel programme om vleisproduksie te verbeter. Direkte oorerflikheid skattings was 0.31±0.14, 0.09±0.02 en 0.14±0.003 vir die geboorte gewig, voor-speen gewig en speen gewig onderskeidelik met die gebruik van ‘n enkel-faktor analise vir dir Ile de France skaap ras. Maternale effekte was beduidend vir al die eienskappe wat bestudeer was , ten spyte van die onvermoë om dit behoorlik te verdeel in hul komponente weens die verlies van genetiese bande dwarsoor die generasies wat uitvloei vanaf ‘n swak data struktuur. Genetiese, fenotipiese en omgewings korrelasies was geskat deur gebruik te maak van ‘n drie-faktor analise en was gevind om laag tot matig te wees vir die vroeë groei eienskappe. Direkte genetiese en maternale permanente omgewings ratios was bereken en dit het nie veel verskil van die resultate verkry deur die enkel-faktor analise. Die aanvaarbare genetiese parameter skattings verkry in hierdie studie het gelei tot die gevolgtrekking dat die Ile de France geselekteer kan word as teelramme in kruisteel programme. Genetiese parameters was geskat vir vroeë groei eienskappe in die Merino Landskaa ras. REML skattings van geboorte gewig, voor-speen gewig en speen gewig was verkry deur diere modelle in enkel-faktor analises. Die direkte oorerflikheid skatting vir geboorte gewig was 0.23±0.13 met die gebruik van die diere model met additiewe direkte genetiese effekte en ooi permanente omgewings faktore as die enigste ewekansige faktore. Die ooi permanente omewings effek vir geboorte gewig was 0.10±0.07. Direkte oorerflikheid vir voor-speen gewig was 0.36±0.05 en die ooi permanente omgewings effek 0.56±0.03. Speen gewig was geskat deur die gebruik van ‘n diere model wat die direkte additiewe effekte en die ooi permanente omgewings effekte bevat het. Die direkte oorerflikheids skatting vir speen gewig was 0.17±0.03. Maternale genetiese effekte was geskat as 0.02±0.01. Genetiese en fenotipiese tendense is verkry vir vroeë lamgewigte in die Dormer-, Ile de France- en Merino Landskaaprasse. Die eienskappe wat oorweeg is, was geboortegewig, voor-speengewig, speengewig en naspeengewig. Voor-speengewigte was net beskikbaar was vir die Ile de France- en die Merino Landskaap rasse en die na-speense gewigte net vir die Dormerras. Die Dormer het beduidende verbetering vertoon in die fenotipiese en genetiese aspekte vir vroeë lamgewigte gedurende die 17 jaar van evaluasie (1990-2007). Die gemiddelde voorspelde direkte teeltwaarde van speen gewig het met 0.12% per jaar gestyg gedurende die 17- jaar periode. Na-speen gewig het met 0.32% per jaar verbeter. By die Ile de France het ‘n toename in die voorspelde teelwaarde van geboortegewig (0.025% per jaar) voorgekom. Gemiddelde direkte teelwaardes vir voor-speengewig het toegeneem teen ‘n jaarlikse tempo van 0.23% en speengewig het met 1.21% per jaar toegeneem. In die Merino Landskaapras het die voorspelde direkte teelwaarde vir geboortegewig met 0.04% per jaar gedaal, terwyl voor-speen- en speengewigte met 0.36% en 0.10% onderskeidelik toegeneem het. Die tendense was ooglopend gekompromiteer weens probleme met die data struktuur, en a.g.v van die relatief min rekords wat beskikbaar was vir die analise in die ras. Dit was duidelik dat die additiewe genetiese variasie beskikbaar was vir al die vroeë groei eienskappe in al die drie rasse. Alhoewel voldoende genetiese variasie vir wesentlike genetiese vordering beskikbaar was, is daar slegs matige vordering verkry vir al die eienskappe in al drie rasse. Die enigste moontlike uitsondering was speengewig in die Ile de France ras, wat met 1.21 % per jaar gestyg het. Alle veranderinge was minstens in die gewensde rigting. Telers word versoek om data deurlopend en akkuraat aan te teken , aangesien een van die groot tekortkominge met die data van al die rasse ‘n tekort aan deurlopendheid in die indiening van die data aan die NISS was. ‘n Meer verteenwoordigende analise sal uitvoerbaar wees, as daar aan al die bogenoemde aanbeveling voldoen kan word.

Thesis (PhD)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Reproduction and robustness traits are integral in ensuring sustainable, efficient and profitable sheep farming. Increases in genetic gain of reproduction and robustness traits are however, hampered by low heritability coupled with the difficulty in quantification of these traits for traditional selective breeding strategies. The aim of the current study was therefore to identify genomic regions underlying variation in reproduction traits and elucidate quantitative trait loci (QTL) and/or genes associated with reproductive traits. The Elsenburg Merino flock has been divergently selected for the ability to raise multiple offspring and has resulted in a High and a Low line that differ markedly with regard to reproductive output and other robustness traits. The flock thus served as an ideal platform to identify genomic regions subject to selection for reproductive traits. To pinpoint genomic regions subject to selection, a whole-genome genotyping platform, the OvineSNP50 chip, was selected to determine the genotype of more than 50 000 SNPs spread evenly across the ovine genome. The utility of the OvineSNP50 chip was determined for the Elsenburg Merino flock as well as additional South African Merino samples and three other important South African sheep breeds, the Blackheaded Dorper, South African Mutton Merino (SAMM) and the Namaqua Afrikaner. Although genotyping analysis of the Elsenburg Merino flock indicated some signs of poor genotype quality, the overall utility of the genotype data were successfully demonstrated for the South African Merino and the other two commercial breeds, the Dorper and SAMM. Genotyping results of the Namaqua Afrikaner and possibly other indigenous African breeds may be influenced by SNP ascertainment bias due to the limited number of indigenous African breeds used during SNP discovery. Analysis of pedigree, phenotypic records and SNP genotype data of the Elsenburg Merino cohort used in the current study, confirmed that the lines are phenotypically as well as genetically distinct. Numerous putative genomic regions subject to selection were identified by either an FST outlier approach or a genomic scan for regions of homozygosity (ROH) in the High and Low lines. Although annotated genes with putative roles in reproduction were identified, the exact mechanism of involvement with variation in reproduction traits could not be determined for all regions and genes. Putative ROH overlapped with QTL for several reproduction, milk, production and parasite resistance traits, and sheds some light on the possible function of these regions. The overlap between QTL for production and parasite resistance with putative ROH may indicate that several, seemingly unrelated traits add to the net-reproduction and may have been indirectly selected in the Elsenburg Merino flock. A SNP genotyping panel based solely on reproduction traits may therefore be ineffective to capture the variation in all traits influencing reproduction and robustness traits. A holistic selection strategy taking several important traits, such as robustness, reproduction and production into account may as such be a more effective strategy to breed animals with the ability to produce and reproduce more efficiently and thereby ensure profitable and sustainable sheep farming in South Africa.
AFRIKAANSE OPSOMMING: Reproduksie- en gehardheids-eienskappe is noodsaaklik om volhoubare, doeltreffende en winsgewende skaapboerdery te verseker. ‘n Toename in genetiese vordering in reproduksie- en gehardheids-eienskappe word egter bemoeilik deur lae oorerflikhede tesame met die probleme in kwantifisering van hierdie eienskappe vir tradisionele selektiewe diereteelt strategieë. Die doel van die huidige studie was dus om gebiede in die genoom onderliggend tot variasie in reproduksie-eienskappe te identifiseer en die rol van verwante kwantitatiewe eienskap loki (KEL) en/of gene met reproduktiewe eienskappe te bepaal. Die Elsenburg Merinokudde is uiteenlopend geselekteer vir die vermoë om meerlinge groot te maak en het gelei tot 'n Hoë en 'n Lae lyn wat merkbaar verskil ten opsigte van reproduksie-uitsette en ander gehardheids-eienskappe. Die kudde het dus gedien as 'n ideale platform om genomiese areas onderhewig aan seleksie vir reproduksie-eienskappe te identifiseer. Om vas te stel waar genomiese areas onderhewig aan seleksie gevind kan word, is ‘n heel-genoom genotiperingsplatform, die OvineSNP50 skyfie, gekies om die genotipes van meer as 50 000 enkel nukleotied polimorfismes (ENPs) eweredig versprei oor die skaap genoom, te bepaal. Die nut van die OvineSNP50 skyfie is bepaal vir die Elsenburg Merinokudde sowel as addisionele Suid-Afrikaanse Merinos en drie ander belangrike Suid-Afrikaanse skaaprasse, die Swartkop Dorper, Suid-Afrikaanse Vleismerino (SAVM) en die Namakwa Afrikaner. Hoewel genotipe resultate van die Elsenburg Merino kudde sommige tekens van swak genotipe gehalte getoon het, kon die algehele nut van die genotipering resultate vir die Suid-Afrikaanse Merino en die ander twee kommersiële rasse, die Dorper en SAVM, bevestig word. Genotipering resultate van die Namakwa Afrikaner en moontlik ook ander inheemse Afrika rasse kan deur ENP vasstellingspartydigheid beïnvloed word as gevolg van die beperkte aantal inheemse Afrika rasse gebruik tydens ENP ontdekking. Ontleding van stamboom inligting, fenotipe rekords en ENP genotipe data van die Elsenburg Merino-kohort gebruik in die huidige studie, het bevestig dat die lyne fenotipies asook geneties verskil. Talle vermeende genomiese areas onderhewig aan seleksie is geïdentifiseer deur 'n FST uitskieter benadering of deur ‘n genomiese skandering vir gebiede van homogositeit (GVH) in die Hoë en Lae lyne. Hoewel geannoteerde gene met potensiële rolle in reproduksie geïdentifiseer is, kan die presiese meganisme van betrokkenheid by variasie in reproduksie-eienskappe nie bevestig word vir al die gebiede en gene nie. Vermeende GVH oorvleuel met KEL vir 'n paar reproduksie-, melk-, produksie- en parasietweerstand-eienskappe, en werp daarom lig op die moontlike funksie van hierdie gebiede. Die oorvleueling tussen KEL vir produksie en parasietweerstand met vermeende GVH kan daarop dui dat 'n hele paar, skynbaar onverwante, eienskappe bydrae tot net-reproduksie, wat indirek geselekteer mag wees in die Elsenburg Merino-kudde. ‘n ENP genotiperingspaneel uitsluitlik gebaseer op reproduksie-eienskappe mag daarom onvoldoende wees om die variasie in alle eienskappe wat betrekking het op reproduksie- en gehardheids-eienskappe, in te sluit. ‘n Holistiese seleksie strategie wat verskeie belangrike eienskappe, soos gehardheid, reproduksie en produksie in ag neem, mag ‘n meer effektiewe strategie wees om diere te teel met die vermoë om in 'n meer doeltreffende manier te produseer en reproduseer en om daardeur winsgewende en volhoubare skaapboerdery in Suid-Afrika te verseker.

Thesis (MScAgric)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The application of assisted reproductive biotechnologies in sheep flocks is hampered by the susceptability of ovine sperm to cryodamage. There is still considerable scope in the improvement of cryopreservation protocols for ovine sperm to minimize the degree of damage to sperm during the cryopreservation process. Pre-cryopreservation processing has a definite effect on the survivability, motility, and fertilizing ability of sperm. Little information is however available on the potential contribution of the genetic make-up of rams, divergently selected for fecundity, on the ability of sperm to offer resistance to the damage caused by cooling, cryopreservation and thawing. The study aimed to investigate the influence of genetic selection for prolificacy (i.e. High Merino Line and Low Merino Line in terms of fecundity) on the ability of ovine sperm to offer resistance to cryodamage. The study investigated the effect of pre-cryopreservation processing by comparing motility and morphometry traits recorded for fresh- and post-thaw Merino ejaculated and epididymal sperm samples obtained form the High and Low lines, respectively. The effect of different sperm concentrations, equilibration periods and the addition or omission of seminal plasma from cryopreserved samples on the viability and morphometrical traits were also investigated. Ejaculate samples were collected by means of the artificial vagina (AV) method from 8 High Line rams and 7 Low Line rams. Epididymal samples were collected from 6 rams of each of the High and Low lines respectively, by recovering the epididymal sperm via aspiration from the cauda epididymides post mortem. Ejaculate samples were subjected to macroscopic and microscopic evaluation, and epididymal samples only to microscopic evaluation, for which the Sperm Class Analyzer® program was used for the evaluation of motility and morphometric measurements. Sperm motility recordings were captured at 100 frames per second. From findings of the study, it was concluded that genotype had no positive influence on the conception rate of the ewes mated to the High or Low Line rams, even though the rams from the two lines differed significantly in terms of their serving capacity. When sperm morphometry was evaluated for fresh ejaculate samples, the two lines differed significantly in terms of the morphometric traits elongation and ellipticity. Epididymal and ejaculated sperm obtained from Low Line rams had broader and rounder heads, compared to sperm obtained from High Line rams. When morphometry was assessed for sperm samples between the two methods of sperm recovery (collected with an AV or recovery via aspiration from the cauda epididymides of sacrificed rams), no morphometrical differences were observed. Significant differences were reported for the majority of the sperm motility traits (i.e. percentage motile, rapid-, medium-, slow swimming, curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), and amplitude of the lateral head displacement (ALH)) recorded for ejaculated and epididymal sperm. The motility traits ALH and beat-cross frequency (BCF) analysed for epididymal sperm differed significantly between the two lines. When epididymal sperm were evaluated post-thaw, it became evident that the sperm obtained from the High Line rams had a larger acrosome surface cover when compared to that of the Low Line ram sperm. The addition of seminal plasma to epididymal samples did not result in an improvement of the preservation of sperm motility. It is known from the literature that cryopreservation causes a decrease in sperm head size. Head width was unaffected by cryopreservation with the addition of seminal plasma in this study, indicating a potential benefit with the use of seminal plasma in the cryopreservation protocol of epididymal ram sperm. The study compared two pre-processing techniques, i.e. the more time consuming swim-up technique (SUT) with a more time-efficient ‘flush technique’ (FT) to optimize the pre-processing protocol for motility assessment of sperm samples before cryopreservation of ram sperm. Comparison of the SUT and FT indicated that almost all of the motility parameters measured using the FT compared favourably with those obtained using the SUT. The results indicated that the FT can be used a more time-efficient technique to use for determining the motility of a sperm sample prior to cryopreservation. In conclusion, line differences associated with reproduction were observed in terms of the serving capacity of the rams, with selection for fecundity influencing the morphometric traits elongation and ellipticity for sperm obtained from the two lines. Future studies should be aimed at investigating morphometric traits of ovine sperm, to correlate it with fertilizing ability of sperm post-thaw and ensure optimal cryopreservation processing.
AFRIKAANSE OPSOMMING: Die toepassing van ondersteunende reproduksie tegnieke in skaaptroppe word bemoeilik deur die onvermoë van ram sperme om weerstand teen bevriesingskade te bied. Daar is nog baie ruimte vir die verbetering van die bevriesingsprotokolle vir skaap sperm om die omvang van bevriesingskade te verminder. Voor-bevriesing verwerking het dan 'n besliste uitwerking op die oorlewing, beweeglikheid en bevrugtingsvermoë, van skaap sperme. Min inligting is beskikbaar oor die potensiële bydrae van die genetiese samestelling van ramme wat uiteenlopend op grond van vrugbaarheid geselekteer is, op die vermoë van skaap sperme om weerstand te bied teen die skade wat deur verkoeling, diepbevriesing en ontdooiing, veroorsaak word. Die doelwit van die studie was om die invloed van genetiese seleksie vir fekunditeit (d.i. Hoë Merino Lyn en Lae Merino Lyn in terme van fekunditeit) op die vermoë van skaap sperme om weerstand teen bevriesingskade te bied, te ondersoek. Die studie het getoets wat die bevriesing proses se effek op epididimale sperme is, deur sperm motiliteit en -morfometrie te vergelyk tussen vars gekollekteerde sperme en sperm monsters na ontdooiing. Die effek van verskillende sperm konsentrasies, ekwilibrasie tydperke en die byvoeging of uitsluiting van seminale plasma op die lewensvatbaarheid en morfometriese eienskappe van Merino ramsperme is ondersoek in die studie. Geëjakuleerde monsters is versamel met behulp van 'n kunsmatige vagina (AV) van 8 Hoë Lyn en 7 Lae Lyn ramme. Epididimale monsters is verkry van 6 ramme van elk van die Hoë en Lae Lyne, deur middel van aspirasie van die sperme uit die cauda epididimii nadoods. Geëjakuleerde sperm monsters is met behulp van makroskopiese en mikroskopiese metodes geëvalueer, en epididimale sperm monsters slegs mikroskopies geëvalueer, met behulp van die Sperm Class Analyzer® program wat vir die evaluasie van beweeglikheid en morfometriese afmetings gebruik is. Sperm beweeglikheids opnames is opgeneem teen 100 raampies per sekonde. Die resultate van die studie het aangedui dat genotipe geen effek het op besetting van die ooie gepaar met die Hoë of Lae Lyn ramme gehad het nie, terwyl die dekvermoë aansienlik tussen ramme van die twee lyne verskil het. Wanneer die morfometriese eienskappe van vars geëjakuleerde sperme vergelyk was, het die lyne beduidend in terme van die morfometriese eienskappe van verlenging (elongation) en elliptisiteit verskil het. Die epididimale en geëjakuleerde sperme verkry vanaf die Lae Lyn ramme het ʼn breër en ronder kopvorm getoon as sperme wat verkry is van die Hoë Lyn ramme. Wanneer die morfometriese eienskappe van sperme versamel met die twee verskillende metodes (d.i. kunsmatige vagina of aspirasie vanuit die cauda epididimides) vergelyk was, is geen morfometriese verskille waargeneem nie. Die meeste sperm beweeglikheidseienskappe (d.i. persentasie beweeglike, vinnig-, medium- en stadig-swemmende sperme, VCL, VSL, VAP en ALH) van geëjakuleerde en epididimale sperme het verskil. Die beweeglikheidseienskappe amplitude van die laterale verplasing van die spermkop (ALH) en frekwensie waarmee sperm sy eie pad kruis (BCF), soos bepaal vir epididimale sperme, het beduidend tussen die twee lyne verskil. Met die evaluering van epididimale sperme na ontdooiing was dit duidelik dat sperme verkry van die Hoë Lyn ramme 'n groter mate van akrosoom-oppervlak gehad het, in vergelyking met sperme van die Lae Lyn ramme. Die byvoeging van seminale plasma by epididimale monsters het nie bygedra tot 'n verbetering van spermbeweeglikheid nie. Bestaande literatuur dui aan dat diepbevriesing 'n afname in die kopgrootte van sperme veroorsaak. In hierdie studie het die byvoeging van seminale plasma ʼn verandering in kopgrootte voorkom, wat dui op ʼn potensiële voordeel om seminale plasma in die bevriesingsprotokol van epididimale ramsperme in te sluit. Die studie het twee beweeglikheid bepalingstegnieke vergelyk om te bepaal of die tydrowende “opswem” tegniek (SUT) vervang kan word met 'n meer tyd-doeltreffende "spoel tegniek” (FT) in die voorbevriesing verwerking protokolle van ram sperme. Vergelyking van die twee tegnieke het aangedui dat die meeste van die kinematiese eienskappe van die FT gunstig met die waardes soos verkry met die SUT, vergelyk het. Resultate het getoon dat die FT parameters goed vergelyk met die beweeglikheid parameters van die SUT, dus kan dit aangeneem word dat die FT ʼn meer tyd-doeltreffende tegniek is wat vergelykbare sperm beweeglikheidsinligting oor skaap sperm monsters voor bevriesing sal verskaf. In samevatting is verskille in terme van die dekvermoë en op morfometriese vlak, meer spesifiek die eienskappe van verlenging (elongation) en elliptisiteit, tussen die twee lyne waargeneem. In toekomstige studies moet die morfometriese eienskappe van skaapsperme verder bestudeer word, asook die korrelasie daarvan met die bevrugtingsvermoë na ontdooiing bepaal om sodoende die diepbevriesing protokolle van skaapsperme te optimaliseer.

Thesis (M. Tech. Agriculture) -- Central University of Technology, Free state, 2012
Low lifetime rearing success and high perinatal mortality have been associated with small pelvic areas of ewes. Ewes with small pelvic areas are more prone to experience dystocia during parturition and high perinatal mortality. It would thus make sense to include pelvic area as criterion in selecting breeding animals (rams) in an attempt to assure bigger pelvic areas in the female progeny as the heritability of pelvic area ranges between 50-60%. The aims of this study were to develop two instruments to accurately measure the pelvic area and rump slope in small stock, to investigate the hindquarter dimensions and to quantify the relationship between a number of easy to measure external body measurements and pelvic dimensions of Dorper sheep. The pelvic meter developed was pre-tested on 90 sheep prior to slaughtering at an abattoir and shortly after slaughter. The correlation between the pre- and post- slaughter measurements was highly significant (P <0.05; r = 0.85). In this study 272 Dorper and White Dorper rams (5-7 months of age) participating in the Northern Cape Veldram project and 332 young Dorper and White Dorper ewes (±12 months of age) from three different breeders were measured. The inside pelvic area was measured trans-rectally. The rams’ pelvic areas were measured five times transrectally, at 40 days intervals between the ages of 223 ± 41 and 385 ± 41 days of age. The height of the pelvis was obtained by measuring the distance between the dorsal pubic tubercle on the floor of the pelvis and the sacrum (spinal column) on the top. The width of the pelvis was measured as the widest distance, between the right and the left shafts of the ilium bones. The pelvic area was calculated using the π (PH/2)*(PW/2) formula. Other linear body measurements (body height, shoulder height, chest depth, forequarter width, hindquarter width, rump length) as well as body weight were taken. The rams’ rump slope was measured in degrees with an instrument that was developed for this purpose, and the ewes’ rump slope was visually scored on a scale from 1-5 with one being very flat and five being very droopy. The overall mean pelvic area of ewes 35.44 ± 4.89 cm2 and those of the rams 28.22 ± 3.21 cm2 differed with 7.22 cm2. Stud ewes recorded significantly larger (P <0.05) pelvic areas (37.38 ± 4.3 cm2) than commercial ewes (33.92 ± 3.77cm2). Results indicated that there are no significant correlations between pelvic dimensions and other body measurements considered in this study, indicating the need to measure pelvic area directly. Both the pelvic meter and rump slope meter, specially developed for this study, proved to be accurate and relatively practical to use in Dorper sheep.

The overall accuracy, efficiency and profitability of livestock improvement strategies can be greatly increased by incorporating quantitative genetics into livestock selection and breeding. Since the introduction of quantitative genetics, a range of traits describing the animal e.g. in terms of health, growth, fecundity, production, have been extensively evaluated in terms of genetics and are now commonly manipulated through breeding to achieve specific selection goals. An industry led enquiry as to the possibility of including spine traits in genetic selection to increase back length in sheep was the basis of the present thesis. Collecting information on spine traits (spine length, vertebrae length and vertebrae number) is of particular interest and use to the sheep breeding industry as there may be the potential to increase meat yield from the highly valuable longissimus thoracis et lumborum (LTL or loin), located parallel to the spine, with little associated change in production costs. The thesis focusses on the use of X-ray computed tomography (CT) scanning as a technique which would allow spine traits to be measured in vivo, hence being useful for genetic selection. The topogram scans produced from the CT scanning procedure were analysed to derive spine trait information for the thesis. The scans were from Scottish Blackface (maternal breed stock), Texel (terminal sire breed), Texel cross Mule and Poll Dorset cross Mule (three-way cross slaughter lambs) so as to represent the divergent genotypes found across the different levels of the United Kingdom’s (UK) three-tier crossbreeding structure of sheep. The present study explored as a first step intra- and inter-operator repeatability of assessment of spine traits from CT derived topograms, as a means to investigate the suitability of the approach for widespread uptake within industry where operators will vary. The results showed that there was high repeatability for intra- and inter-operator assessment of spine trait measurements verifying that the CT method could be accepted as a reliable alternative (to slaughter for example) to quantify spine traits. To determine whether spine traits are similar across the range of breeds representing the key genotypes and crosses in the UK sheep industry, numerous CT topograms were analysed. The results showed marked variation in spine traits within and between Scottish Blackface, Texel, Texel cross Mule and Poll Dorset cross Mule breeds and crosses. For example, the Texel breed was found to have the largest within-breed range for thoracolumbar vertebrae number (17 – 21; the majority possessing 19), but the spine length of these animals was, on average, significantly shorter than the other breed/cross groups. The present study concluded that the significant differences between the breeds and breed types for the particular spine traits were possibly indicative of a genetic control for these traits. Furthermore, investigation into the phenotypic correlations between spine and production traits revealed some directional associations which may prove beneficial for meat production. For example, Scottish Blackface lambs which had a longer length of a specific spine region had an associated decrease in the volume of carcass fat. Texel lambs which had a longer length of a specific spine region had a slightly larger loin muscle area, at a given weight. The present study also examined animals from a population of Texel lambs already heavily selected for increased muscling. The Texel muscling quantitative trait locus (TM-QTL), segregating in these animals and generally in the UK’s Texel sheep population, is expressed through a polar overdominance pattern of inheritance and its effect on the loin (localised muscle hypertrophy) is commonly utilised in the selection and breeding of Texel sheep to improve meat production. Examination of topograms from lambs bearing the whole range of TM-QTL genotypes showed little evidence to suggest that the change in loin shape/increased loin muscling, as a result of the TM-QTL and its inheritance, has led to any associated change in the underlying spine characteristics. This suggests that selection for increased muscling associated with the TM-QTL may be achieved independently of changes in the spine traits studied. The potential to breed for certain spine traits to increase vertebrae number and hence chops or loin yield can be enhanced by establishing the genetic parameters for the traits. The present study employed a collection of performance trait records from Texel lambs to provide the basis for genetic analysis. The results showed different levels of heritability for the different spine traits but also high standard errors. For example, heritability of vertebrae number was dependent on vertebra location: for thoracic vertebrae heritability was high (ℎ2 = 0.99; SE = 0.42), for lumbar vertebrae heritability was low (ℎ2 = 0.08; SE = 0.12), whereas in contrast, thoracolumbar vertebrae heritability was moderate (ℎ2 = 0.44; SE = 0.27). Phenotypic and genetic correlations between all combinations of traits were also obtained. Accurate predictions of the size and direction of response to selection can be achieved through such genetic analysis of traits. The more that is known of the genetic characteristics of traits and their genetic correlations with other economically important traits, the more efficiently it can be built into breeding programmes improving the overall performance of stock. The results of this study showed that providing spine measurements can contribute to the diversity of trait information available to breeders. The present study also suggests that there may be opportunities to select for increased spine length/vertebrae number which would benefit the sheep industry in terms of increased chop number/loin yield. Although more data are needed prior to implementation. Practical uptake of selection for spine traits would be enhanced due to the straightforward nature of the measurements and the high operator repeatability.

Thesis (Ph. D.)--West Virginia University, 2003.
Title from document title page. Document formatted into pages; contains vi, 187 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 156-183).

Thesis (Ph. D.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains ix, 144 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 126-144).

Two sheep group breeding schemes were considered in this study to examine the genetic progress made over a 20 year period and the success of running such schemes in practice. The data were records of lamb weaning weight in the CAMDA scheme (Welsh Mountain breed) and the Lleyn scheme (Lleyn breed), collected between 1976 and 1996. After the edits, a total of 31,161 records for the CAMDA and 29,090 records for the Lleyn scheme were available for the analyses. The estimates of the heritability of weaning weight for individual flocks were low to moderate. In the CAMDA scheme, the estimates of the direct and maternal heritability values ranged from 0.04 to 0.43, and 0.03 to 0.11, respectively. The ratio of temporary environmental variance over the total variance ranged between 0.13 to 0.35. The estimates of total heritability values in flocks of 12 and 18 weeks of age were in the range of 0.23-0.45 and 0.07-0.18, respectively. In the Lleyn scheme, the estimates of the ratio of temporary environmental variance over the total variance, and the direct and maternal heritability values ranged from 0.15 to 0.39, 0.03 to 0.31, and 0.04 and 0.23, respectively. The estimates of the total heritability values in individual flocks of the scheme ranged from 0.07 to 0.33. The differences in heritability values between the flocks, reflected the differences in the model of analysis fitted, and size and structure of the data available for individual flocks of the scheme. It is concluded that group breeding schemes are a viable means of improving the production of traits of a breed, but that more attention should be paid in the setting up of the schemes, to a scoring system which will accurately reflect the market value of the stock. The application of group breeding schemes in Iran would require taking account of the differences in the social and climatic environments. Much greater attention would be needed to determine the selection objectives and these would need to be properly included in the selection index.

Este relatório refere-se ao estágio curricular de Mestrado Integrado em Medicina Veterinária. Será em primeiro lugar apresentada a casuística referente às atividades desenvolvidas durante o estágio, tirando algumas elações sobre as suas frequências relativas e absolutas. Numa segunda fase do relatório, será abordada uma área específica de interesse, nomeadamente sobre sistemas de produção de ovinos de leite. O objetivo do sistema de produção será conseguir uma exploração especializada, que permita obter um máximo de produtividade. Para a otimização da exploração são apresentados planos de profilaxia, de maneio reprodutivo, de maneio alimentar e de maneio geral. A exploração em causa conta com um efetivo de 585 animais de raça Lacaune; Medicine and surgery in livestock species Abstract: This report refers the curricular internship of Integrated Master Course in Veterinary Medicine. Firstly there will be presented the activities developed during the internship, commenting the methods and its relative and absolute frequencies. In a second part of the report, it will be developed a specific area of interest, about a dairy sheep production system. The production system objective is to obtain a specialized farm with, maximum productivity. For the optimization of the operation, plans for prophylaxis, breeding management, feeding and general management will be presented. The farm study will be designed with 585 ovine of the Lacaune breed.

Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.

In Graaff-Reinet, domestic livestock farming and springbuck ranching are similar in that they both rely on the rangeland for their sustainability. However, as a consequence of repeated monotonous domestic livestock farming, resulting in compromised biological productivity and diversity, the rangelands have disintegrated. This, unfortunately, has placed the future sustainability of these rangelands and the livelihoods of the local people in an indeterminate state. In recent years, there has been an increasing interest in springbuck ranching for meat production as an alternative to domestic livestock farming in the area following (a) fears of worsening environmental challenges; (b) declining profitability in commercial domestic livestock farming and; (c) growing calls for the sustainable use of these rangelands for the benefit of future generations. The springbuck has emerged as a credible alternative to utilising the rangelands - as opposed to sheep - because of its promise to addressing the above challenges. This is in an attempt to tap into the multitude of benefits that the springbuck possesses (by virtue of being part of the natural capital of the area) that have a potential towards restoring ecological integrity by extenuating some of the detrimental effects of sheep farming on the rangelands and presenting opportunities for diversifying incomes. Yet, despite the general increase in interest, a resistance towards the uptake of springbuck ranching for meat production exists. The main contention is that springbuck meat production cannot out-perform the economic returns of wool sheep farming. This study attempts to address these concerns by investigating the profitability and economic sustainability of converting a sheep farm into a springbuck ranch in Graaff-Reinet. The study uses stochastic simulation to estimate the probability distribution of some key output variables, namely: net cash income, ending cash balance, real net worth and the net present value (NPV) in evaluating the profitability of converting a 5 000ha sheep-dominated farm into a springbuck-dominated ranch under three alternative scenarios. The use of stochastic simulation allows for the incorporation of downside risk associated with the production and marketing of wool, mutton and springbuck meat. The study uses stochastic prices and yields to calculate net returns variability. Incorporating scenario analysis helped to evaluate how alternative wool sheep-dominated and springbuck-dominated combinations would perform based on the probable outcomes of different assumptions in the various scenarios. By applying stochastic efficiency with respect to a function (SERF) criterion to the simulated NPVs, this study compares the profitability of alternative scenarios based on various risk aversion coefficients. The study finds that converting a 5 000ha wool sheep dominated farm into a springbuck dominated ranch could potentially be a more profitable investment than wool sheep farming over a 15 year planning horizon, in Graaff-Reinet. The SERF results indicate that for all scenarios tested, the best strategy of converting a wool sheep dominated farm into a springbuck ranch would be one which comprise a combination of 70% springbuck, 20% mutton and 10% wool production as the likely profitable enterprise mix. Using economic sustainability analysis, the study reveals that because of low costs in springbuck ranching, springbuck meat production enterprises are most likely to be more financially sustainable than wool sheep-dominated enterprises. This suggests that rangeland owners may be better off converting their wool sheep-dominated farms into springbuck-dominated ranches. Thus, as the call for more environmentally benign rangeland utilising economic-ecological systems intensifies, rangeland owners in the Eastern Cape Karoo have a practicable option. At the very least, there exists an option to broaden their incomes whilst promoting ecological restoration with springbuck meat production.

Orientador: Felix Guillermo Reyes Reyes
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: A ovinocultura vem despertando enorme interesse em todas as regiões do Brasil e sua produção destina-se, principalmente, na criação de cordeiros. Contudo, um dos grandes impasses nos sistemas de produção, especialmente em pastagens, são as parasitoses gastrointestinais. Os problemas associados com os parasitas acarretam danos à saúde dos animais, reduzindo o seu desempenho e os lucros do produtor. Como medida profilática, faz-se uso dos anti-parasitários, medicamentos veterinários com ação contra endo e ectoparasitas. Contudo, a utilização indiscriminada dos fármacos tem favorecido o desenvolvimento de estirpes resistentes responsáveis pela rápida ineficácia do composto. Como medida de controle dos nematoides gastrointestinais nas criações comerciais de ovinos, o fármaco costuma ser administrado baseando-se no resultado de duas formas de exame diagnóstico: contagem de ovos dos parasitas nas fezes e o teste FAMACHA® (exame da coloração da mucosa ocular) ou a aplicação do composto em períodos regulares de 28 dias, independente de exame. Na tentativa de determinar a melhor posologia (dose/frequência) do anti-helmíntico a ser empregado na prática, busca-se o melhor entendimento de suas propriedades farmacocinéticas, ou seja, determinar a quantidade do fármaco disponível no organismo para geração de um efeito terapêutico adequado. A moxidectina (MOX) é uma lactona macrocíclica que tem se destacado nos últimos anos pela sua eficiência anti-helmintica em baixas doses e pela longa persistência no organismo dos animais. Deste modo, o presente trabalho teve por objetivo desenvolver e validar um método analítico, empregando cromatografia líquida acoplada a espectrometria de massas (LC-ESI-MS/MS), avaliar o perfil farmacocinético da MOX no soro de cordeiros, assim como comparar as concentrações dos resíduos presentes no soro de animais submetidos a diferentes métodos de controle parasitários em condições de criação comercial em pastagens. O método analítico desenvolvido foi validado apresentando exatidão entre 80-107,3 % e valores de precisão entre 1,7-6,7 %. Os limites de detecção (LOD) e quantificação (LOQ) determinados foram de 2,0 ng mL-1 e 5,0 ng mL-1, respectivamente. Os resultados dos parâmetros de validação demonstraram que o método foi adequado para determinar a presença da MOX no soro de cordeiro. A disposição da MOX no soro foi avaliada em cordeiros da raça suffolk (n=7), após administração subcutânea de 0,2 mg kg-1 de peso corpóreo, em uma única dose. As concentrações de MOX no soro apresentaram valores de Cmáx 8,5 ± 2,81 ng mL-1, e Tmáx de 1 ± 0,7 dias. Os valores da AUC 0-8 e T1/2 foram 82,42 ± 8,02 ng dia.mL-1 e 7,66 ± 1,62 dias, respectivamente. Os resultados indicam uma absorção subcutânea lenta e, portanto, maior tempo de exposição sistêmica e menor disponibilidade do fármaco na circulação sanguínea, quando comparado com outras espécies como caprinos, bovinos ou com a ivermectina. Nenhum dos diferentes métodos de controle parasitários avaliados apresentou resíduos de MOX no soro superiores ao limite de quantificação do método
Abstract: The sheep breeding has aroused great deal of interest in all regions of Brazil and its production is mainly intended to the creation of lambs. However, the gastrointestinal parasitosis is one of the major difficulties in the production systems, especially in the field. Parasites cause animals¿ health damage, reducing their performance and the profits of the producer. As a consequence parasiticides are used as prophylactic measure. However, care on their use must be taken, since the indiscriminate use of veterinary drugs has favored the development of resistant strains, responsible for the loss of the drug effectiveness. As a control of gastrointestinal nematodes in the commercial sheep breeding, the veterinary drug is usually administered based on the result of two forms of diagnostic test: faecal egg count of parasites and the FAMACHA® test (examination of ocular mucosa color), or on the application of the veterinary drug at regular periods of 28 days, independently of any diagnostic test. In an attempt to determine the optimal dosage (dose / frequency) of the parasiticide to be used in practice, it is necessary the better understanding of their pharmacokinetic properties, in order to determine the amount of drug available in the body to generate an adequate therapeutic effect. Moxidectin (MOX) is a macrocyclic lactone that acts against endo and ecto-parasites, and has come to prominence in recent years due to its effectiveness at low doses and long persistence in the organism of the animals. Thus, the present study aimed to develop and validate an analytical method employing liquid chromatography coupled to mass spectrometry (LC-ESI-MS/MS), evaluate the pharmacokinetic profile of MOX in the serum of lambs, and to compare the MOX residue levels on the serum of animals subjected to different parasiticidal method of control in conditions of commercial breeding in the field. The validated analytical method presented between 80 to 107.3 % accuracy, and precision values between 1.7 - 6.7 %. The limits of detection (LOD) and quantitation (LOQ) were 2.0 ng mL-1 and 5.0 ng mL-1, respectively. The results of the validation parameters showed that the method was suitable to determine the presence of MOX in the lamb serum. The pharmacokinetic profile of MOX was evaluated in suffolk race lambs (n = 7), after a single subcutaneous dose administration of 0.2 mg kg-1 body weight. The serum concentrations of MOX showed Cmax value of 8.5 ± 2.81 ng mL-1, and Tmax of 1 day. The AUC0-8 and the T1/2 were 82.42 ± 8.02 ng day.mL-1 and 7.66 ± 1.62 days, respectively. The results indicated a slow MOX subcutaneous absorption and, therefore, increased systemic exposure time and low availability of the drug in blood circulation, when compared to other species such as goats or cattle, or to ivermectin. None of the different parasiticidal control methods evaluated showed MOX residue levels above the LOQ of the analytical method
Mestrado
Ciência de Alimentos
Mestra em Ciência de Alimentos

Orientador: Alessandro Francisco Talamini do Amarante
Resumo: Na produção animal o planejamento nutricional inadequado desencadeia grandes prejuízos ao sistema produtivo, trazendo consequências adversas aos animais e menores lucros ao criador. Este trabalho teve por objetivo avaliar a influência da suplementação alimentar sobre a imunidade dos cordeiros, biologia e patogenia de Haemonchus contortus e Trichostrongylus colubriformis. Quarenta e quatro cordeiros machos da raça Dorper com aproximadamente quatro meses e 31,5±3,24 kg de peso corporal foram alocados aleatoriamente em quatro dietas à base de feno triturado, Cynodon dactylon (cv. Tyfton), acrescido de 0%, 25%, 50% ou 75% de concentrado. Em cada dieta sete animais foram infectados com 1.000 larvas infectantes (L3) de H. contortus e 1.000 L3 de T. colubriformis a cada três dias ao longo de 12 semanas. Em cada dieta, quatro animais permaneceram como grupo controle, Não-Infectados. Os grupos experimentais foram: 0%-Infectado, 0%-Não-Infectado, 25%-Infectado, 25%-Não-Infectado, 50%-Infectado, 50%-Não-Infectado, 75%-Infectado e 75%-Não-Infectado. Quanto maior a suplementação, menor a contagem de ovos por grama de fezes (OPG) de H. contortus (P < 0,0001), porém sem influência sobre contagem de OPG de T. colubriformis. O número de fêmeas de H. contortus foi maior no grupo 0% infectado que nas demais dietas (P = 0,0052). Em nenhuma fase parasitária de T. colubriformis houve efeito da Dieta (P > 0,05). Animais da dieta 0%-Infectado tiveram menor volume globular (VG) que seu grupo controle... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor

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Foram avaliadas as características produtivas (ganho de peso e medidas morfométricas) de ovelhas, recém-paridas das raças Santa Inês e Texel, em pastejo intensivo, submetidas à suplementação concentrada, em manejo de cria em aleitamento natural. Além disso, avaliou-se desempenho ponderal (ganho de peso e medidas morfométricas) dos borregos, filhos das mesmas ovelhas, em fase de aleitamento suplementados ou não em sistema de creep - feeding e, posteriormente, em fase de terminação, submetidos a três níveis de inserção de concentrado (0, 400 e 800 g. Animal. Dia-1). Na fase de terminação, foram utilizados 24 cordeiros desmamados. Como procedimento para a avaliação dos tratamentos no estudo das ovelhas e dos borregos em fase de aleitamento, o delineamento experimental utilizado foi o em blocos casualizados, sendo as diferenças entre tratamentos determinadas por meio do teste de F. No ensaio de terminação dos borregos, as variáveis avaliadas foram submetidas à análise de variância, seguido e um ajustamento em regressão linear. Todos os procedimentos inferenciais foram efetuados considerando para a manifestação das diferenças, um erro aleatório máximo de 5%. Não foram encontrado aumento no do peso corporal em nenhuma das duas categorias animal estudadas na fase de aleitamento. Nas características morfométricas, as ovelhas do grupo 2 apresentaram menor altura de garupa. Na fase de terminação os animais suplementados apresentaram melhor desempenho ao apresentarem peso ideal para o abate aos 95 dias, idade em que os animais sem suplementação apresentavam média de peso inferior a 28 kg. Já para morfometria,os animais deste segundo ensaio apresentaram homogeneidade nas características morfométricas.
Productive characteristics evaluated (weight gain and morphometric measurements) of sheep, newly calved of Santa Inês and Texel, intensive grazing, submitted to concentrate supplementation, in nestling management. In addition, it evaluated weight gain (weight gain and morphometric measurements) of lambs, sons of the same sheep in supplemented breast-feeding or not creep system - feeding and later finishing phase, subjected to three levels concentrated insert (0, 400 and 800 g. Animals. Day-1). In the finishing phase, 24 weaned lambs used. As a procedure for the evaluation of treatments in the study of the sheep and lambs in feeding phase, the experimental design was a randomized block, with the differences between treatments determined by the F test in lambs termination assay, evaluated variables subjected to analysis of variance followed and an adjustment in linear regression. All inferential procedures performed considering for the manifestation of the differences, a maximum of 5% random error. There found increase in body weight in either animals categories studied in breast-feeding. In the morphometric characteristics, group 2 ewes had lower height croup. In the finishing phase, the supplemented animals showed better performance when submitting ideal weight for slaughter at 95 days, the age at which animals without supplementation had average weight less than 28 kg. As for morphometry, the animals of the second test showed homogeneity in the morphometric characteristics.

The objective of this study was to determine sheep production practices, constraints, flock dynamics, body condition and weight variation in two ecologically different resource-poor communal farming systems of the Eastern Cape Province of South Africa. Mean sheep flock sizes per household were not significantly different between the two ecologically different areas (villages); Gaga (19.0±3.10) and Sompondo (18.3±3.10). Shortage of feed, disease and parasite were reported the most important constraints across the two villages. In both villages, sheep housing was poorly constructed using acacia brushwoods. Fewer farmers owned rams: the rams to ewes ratio for the two villages were 1:20, 1:19 for Gaga and Sompondo, respectively. The low ram: ewe ratios reported suggest that inbreeding might have been reducing productivity of their flocks. There was also uncontrolled breeding due to undefined and mating seasons. Gall sickness, heart water and footrot caused most of the sheep mortalities. Dohne Merinos were the common genotypes in the two villages. Total entrances for each flock were higher (p < 0.05) in hot-dry season and hot-wet season than in other seasons. Most of the entrances were lambs and were born in hot-dry season (September) and cool-dry season (June) for larger flocks (10.90 ± 3.02) and for small flocks (3.65 ± 3.02). High lamb mortalities were experienced in the post-rainy (April) and hot-wet (December) season. There was a significant interaction between season and flock size. Most of the sales occurred in the hot-wet season. Ecological area had significant effect on sheep production potential (p < 0.05) in both flock classes. The average sheep production efficiency (SPE) value for Gaga and Sompondo were 0.50 ± 0.116 and 0.50 ± 0.096 respectively. The SPE for large flock was higher (p < 0.05) by season and flock size. Large flocks had a higher (p < 0.05) SPE values and the SPE ranged from 1.11 ± 0.193 in April, a post-rainy season month to 1.55 ± 0.193 in December, a hot-wet season month. Lamb mortalities constituted the greater part of outflows. High lamb mortalities occurred in hot-wet (December), hot-dry (September) and post-rainy (April) seasons. There was a significant interaction between season and age of sheep on body weight of sheep. Highest (p < 0.05) body weights were recorded in the post-rainy and autumn season in both lambs and ewes. It is therefore very important to come up with affordable interventions which take into play ecological differences of the areas for improved nutritional status of sheep in communal areas which will lead to improved sheep productivity and the poor-resourced farmer human nutritional and livelihood.

Master of Science
Department of Animal Science and Industry
David M. Grieger
Controlling reproductive cycles during active cyclicity and seasonal anestrous in small ruminants is critical for profitability. The objective of this study was to evaluate the effect on estrous response and interval to estrus of two CIDR protocols in sheep and goats during breeding and non-breeding seasons. In experiment 1, 133 ewes were randomly assigned to 1 of 3 treatments during the breeding season. In the CIDR-7 group, ewes received a CIDR insert for 7 d. In the CIDR-7 + PGF treatment, ewes received a CIDR insert for 7 d and 20 mg of prostaglandin-F[subscript]2[subscript]α (PGF[subscript]2[subscript]α) upon CIDR removal. Ewes in the CIDR-14 treatment received a CIDR insert for 14 d. Following CIDR removal all ewes were exposed to a ram every 12 h until breeding. There was a shorter interval from CIDR removal to estrus in the CIDR-14 treatment compared to the CIDR-7 and CIDR-7 + PGF treatments (P<0.05). There was no difference in number of ewes per treatment displaying estrus. In experiment 2, 54 ewes were randomly assigned to one of two treatment groups during the anestrous season. Ewes in CIDR-7 and CIDR-14 treatments received a CIDR insert for 7 d and 14 d, respectively. Upon CIDR removal ewes were exposed to a ram every 12 h until breeding. There was a significantly shorter interval from CIDR removal to estrus in CIDR-14 ewes when compared with CIDR-7 ewes (P<0.05). For experiment 3, 37 Boer does were randomly assigned to one of two treatments. In the CIDR-10 treatment, does received a CIDR insert for 10 d and 20 mg of PGF[subscript]2[subscript]α at time of CIDR removal. In the CIDR-19 treatment, does received a CIDR insert for 19 d. Upon CIDR removal, does were exposed to a buck fitted with a marking harness and chalk marks were recorded every 12 h. The number of does displaying estrus was not different (CIDR-7, 85%; CIDR-14, 95%). There was no difference in interval from CIDR removal to estrus between treatments. Results from experiments 1 and 2 supported the hypothesis that long-term protocols yield a shorter interval to estrus when compared with short-term protocols.

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Genetic (co)variances for body weight, clean fleece weight and fibre diameter were estimated for the South African Dohne Merino using data transformed as proportions of contemporary group means. The data analysed included body weight, clean fleece weight and fibre diameter records for 282 513 animals, evaluated between 1992 and 2011. There were 5 698 sires, 105 886 dams and 6 291 contemporary groups in the data. A three-trait animal model was fitted, where the random variables were the direct additive genetic effects, as well as the sire-flock-season (SFS) interaction, while the fixed effects included contemporary groups (FYSSM) (6 291 classes), birth status (single, twins or triplets), age of dam (1 to 3 years), which was plotted as a linear regression as well as age at performance measurement, which was fitted as a polynomial. The direct heritability estimates (SE) for body weight, clean fleece weight and fibre diameter were 0.265 (0.005), 0.210 (0.004) and 0.437 (0.005), respectively. Genetic correlations for body weight with clean fleece weight and fibre diameter were 0.035 (0.015) and 0.139 (0.011), respectively, while the genetic correlation between clean fleece weight and fibre diameter was 0.169 (0.012). Body weight had phenotypic correlations of 0.327 (0.002) and 0.150 (0.002), respectively, with clean fleece weight and fibre diameter, which had a phenotypic correlation of 0.190 (0.002) with clean fleece weight. The moderate to high heritability estimates suggests that there is substantial genetic variation, which may result in genetic improvement if selection is applied on these traits. Genetic correlations were generally low, suggesting that progress in all these traits was possible in a scientific selection program. Genetic trends derived during the study supported the contention that genetic progress in all traits was attainable in a well-constructed breeding programme. Transformation of the data to percentages of contemporary groups resulted in adjustments to breeding values. The breeding values for sires originating from flocks maintained in limiting environments (Low group; 180 sires) were adjusted upwards, while those of sires originating from a non-limiting production environment (High group; 146 sires) were adjusted downwards. These effects were markedly obvious for the quantitative traits (body weight and clean fleece weight), but to a much lesser extent for fibre diameter. This transformation resulted in the genetic trends for the Low groups being adjusted to be comparable to those in the High group for body weight and Fibre diameter. It was concluded that sire breeding values derived from transformed data would be more robust across the typical diverse environments supporting local Dohne Merino production. The genetic value of animals entering the recorded population from a commercial base (F4 animals) was below the fully recorded part of the population. The inclusion of phantom parent groups in the genetic analysis rendered genetic trends in F4 animals comparable to that of the pedigreed portion of animals in the analyses. It was concluded that animals from a commercial base (which are alleged to have advantages in terms of fitness and robustness) were more likely to perform satisfactorily for selection with the inclusion of phantom groups than without it. It was recommended that data in the national Dohne Merino analysis be transformed proportion of contemporary group means to account for heterogeneous contemporary group variances. Phantom parent groups should also be applied to the analysis to increase the probability of those animals entering the breeding flock from a commercial base being selected.
AFRIKAANSE OPSOMMING: Genetiese kovariansies vir liggaamgewig, skoonvaggewig en veseldikte is vir die SA Dohne Merino bevolking in Suid-Afrika beraam nadat data getransformeer as ‘n proporsie van die kontemporêre groep gemiddelddes uitgedruk is. Die data het rekords in van liggaamsgewig, skoonvaggewig en veseldikte van 282 513 diere oor die tydperk van 1992 tot 2011 ingesluit. Die data sluit rekords van 5 698 vaars, 105 886 moers en 6 291 kontemporêre groepe in. 'n Meer-eienskapdieremodel met 'n additiewe diere-effekte sowel as 'n vaar-kudde-seisoen (SFS) interaksie is as ewekansige effekte gemodelleer, bykomstig tot die vaste effekte van kontemporêre groep (FYSSM) (6 291 klasse), geboortestatus (enkelling, tweeling of drieling), ouderdom van moer (1 tot 3 jaar) gepas as 'n lineêre regressive, sowel as ouderdom by prestasie meting as ‘n polinoom gepas. Die beraamde direkte oorerflikheid (SF) van liggaamgewig, skoonvaggewig en veseldikte van die meereienskap dieremodel was onderskeidelik 0,265 (0,005), 0,210 (0,004) en 0,437 (0,005). Die genetiese korrelasies van liggaamsgewig met skoonvaggewig en veseldikte was 0,035 (0.015) en 0,139 (0.011) onderskeidelik, terwyl die genetiese korrelasie tussen skoonvaggewig en veseldikte 0,169 (0.012) beloop het. Liggaamsgewig het onderskeie fenotipiese korrelasies van 0,327 (0.002) en 0.150 (0.002) met skoonvaggewig en veseldikte gehad, terwyl skoonvaggewig ‘n fenotipiese korrelasie van 0.190 (0.002) met veseldikte gehad het. Die medium tot hoë oorerflikheidhede dui daarop dat daar aansienlike genetiese variasie voorkom, wat kan aanleiding gee tot genetiese vordering as seleksie op die eienskappe toegepas word. Genetiese korrelasies was oor die algemeen laag wat daarop dui dat vordering in al die eienskappe deur ‘n wetenskaplike seleksie program moontlik is. Die aanspraak is deur genetiese tendense in die studie bevestig. Die transformasie van data na proporsies van kontemporêre groep gemiddeldes het daartoe gelei dat teelwaardes aangepas word. Die teelwaardes van vaars uit kuddes met ‘n omgewing wat beperk word (Lae groep:180 vaars), is opwaarts aangepas. Daarenteen is vaars uit 'n nie-beperkende produksie omgewing (Hoë groep:146 vaars) se teelwaardes afwaarts aangepas. Hierdie effekte was veral ooglopend vir die kwantitatiewe eienskappe, liggaamgewig en skoonvaggewig, maar tot 'n mindere mate vir veseldikte. Die transformasie het daartoe gelei dat die genetiese tendense for die Lae groep aangepas word om vergelykbaar te wees met die Hoë groep vir liggaamsgewig en skoonvaggewig. Die gevolgtrekking was gemaak dat meer toepaslike vaar teelwaardes, bereken vanaf getransformeerde data, verkry word vir regoor die diverse omgewings wat produksie van plaaslike Dohne Merinos ondersteun. Die genetiese waarde van diere wat die aangetekende populasie uit ‘n kommersiële agtergrond (F4 diere) binnekom was laer as die volledig aangetekende gedeelte van die populasie. Die insluiting van skimgroepe in die genetiese ontleding het tot genetiese tendense gelei wat die F4 diere vergelykbaar gemaak het met diere in die ontleding wat wel stamboekinligting het. Die gevolgtrekking is gemaak dat diere van ‘n kommersiële agtergrond (wat aanvaar word om voordele in te hou in terme van fiksheid en robuustheid) meer geredelik geselekteer sal word vir die stoet met die insluiting van skimgroepe as daarsonder. Dit word aanbeveel dat die data in die Nasionale Dohne Merino na proporsies van die kontemporêre groepgemiddeldes getrensformeer word om vir heterogene kontemporêre groep variansies voorsiening te maak. Skimgroepe moet ook gepas word in die ontleding om die waarskynlikheid te verhoog dat diere vanuit 'n kommersiële basis, ook geselekteer sal word.

La sélection génomique (SG) des animaux et des plantes a été rendue possible grâce aux avancées des biotechnologies, notamment des puces à ADN de haute densité et de faible coût. Son efficacité et sa profitabilité a été clairement démontrée chez les bovins laitiers, où elle a été très rapidement mise en pratique. En revanche, son application pour les petits ruminants est encore limitée, et, notamment, n’a pas démarré en France. Ses potentialités sont toutefois à l’étude dans quelques programmes concernant les ovins et caprins laitiers, et les responsables des filières correspondantes désirent connaitre l’efficacité de cet outil dans leur situation. Cependant, la prudence est de règle, compte tenu des différences entre les schémas de sélection des bovins laitiers et des petits ruminants. Cette étude fait partie d’un programme entrepris pour évaluer l’utilisation et la gestion de l’information génomique dans les schémas de sélection ovin et caprin. Au cours de cette thèse ont été examinés (1) l’impact de la SG sur le gain génétique dans des schémas de sélection de petits ruminants, (2) l’efficacité économique de la SG en petits ruminants, en prenant l’exemple d’un programme de sélection ovin-viande; (3) l’importance d’une optimisation de certaines décisions (quantifiées par des variables dans un modèle décrivant les schémas) pour maximiser le progrès génétique et (4) une piste contribuant à l’optimisation de la population de référence. Les modèles utilisés appartiennent au champ des méthodes déterministes et les exemples ont porté sur les schémas de sélection existants (ovins laitiers, ovins viande et caprins laitiers). Les résultats de cette étude suggèrent que la sélection génomique peut être plus rentable que la sélection classique en terme de gain génétique, à condition qu’une population de référence de taille moyenne soit disponible (environ 2000 individus). Ils montrent, en particulier dans les schémas laitiers, que le potentiel de la SG de réduire l’intervalle de génération pourrait fortement augmenter le gain génétique. Dans le schéma ovin allaitant modélisé, combiner l’information génomique et les phénotypes de caractères bouchers donne plus de gain génétique que la sélection classique ou la SG sans phénotype sur les candidats. En termes d’impacts économiques, les résultats du schéma ovin allaitant modélisé montrent que toutes les stratégies de sélection génomiques sont plus onéreuses que la sélection classique. Cependant, les gains marginaux (recettes totales moins coûts variables) de certains scénarii de SG s’avèrent légèrement plus élevés que pour la sélection classique. L’étude montre également, dans tous les schémas et stratégies de sélection, que l’optimisation de l’utilisation de variables de décision pourrait grandement augmenter le gain génétique et l’efficacité économique, par rapport aux situations actuelles. Avec cette étude, on peut conclure que la mise en place de la sélection génomique dans les programmes de sélection des petits ruminants est possible et pourrait être plus bénéfique que la sélection classique dans certains cas. Cependant, il y a plus d’obstacles par rapport aux bovins laitiers, en particulier, la construction d’une population de référence fiable et des coûts élevés de génotypages par rapport à la valeur des candidats à la sélection. Ces obstacles pourraient freiner sa mise en œuvre, voire l’empêcher dans certaines races
Implementing genomic selection (GS) in small ruminant breeding programs is still at the research and development level. This new way of selection in animals and plants was made possible thanks to the development of low costs, high density SNP chips. It proved to be highly beneficial in dairy cattle breeding programs. The French small ruminant industries are strongly interested in evaluating the efficiency of this tool in their situation. However, they are also very cautious given the inherent differences in terms of capacity and functionalities between dairy cattle and small ruminant breeding programs. This study is part of bigger efforts mobilized to evaluate the use and management of genomic information in sheep and goats breeding programs. The PhD work examined (1) the impact of genomic selection on genetic gain of small ruminant breeding programs; (2) the economic efficiency of genomic selection in small ruminant, through an example of a meat sheep breeding program; (3) the benefits of optimizing the use of decision variables on genetic gain; and (4) contributed some ideas on how to optimize the choice of individuals in the reference population. The modeling parts were done by deterministic methods and the examples focused on the existing breeding programs (dairy sheep, meat sheep and dairy goats) with medium to small size breeding units. The results of this study suggest that adopting genomic selection can be more profitable than classic selection in terms of genetic gain, provided that, at least, a medium size reference population is available (around 2,000 individuals). They show, especially in dairy breeds, that the GS potentials of reducing generation interval could greatly increase the genetic gain. In meat sheep breeding program, exploring the possibility of combining genomic information and meat phenotypes gave higher genetic gain than classic or pure genomic selection. In terms of economic impacts, results of the meat sheep breeding program we modeled show that all genomic selection strategies are more expensive than classic selection. However, the contribution margins (total revenues minus total variable costs) of some GS variants were slightly higher than benefits from classic selection. The study also shows, across breeds and selection strategies, that optimizing the use of decision variables could greatly increase the genetic gain and benefits, compared to the current situation. With this thesis we can conclude that adopting genomic selection in small ruminant breeding programs is possible and could be more beneficial than classic selection in some cases. However, there are more obstacles compared to dairy cattle, especially, construction of reliable reference populations and high costs of genotypes relative to the value of selection candidates. These might delay implementation in general or prevent it in some breeds

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Objetivou-se avaliar os efeitos das dietas com e sem a inclusão de extrato etanólico de própolis Verde Alecrim no consumo de matéria seca, nos parâmetros de perfil metabólico sanguíneo e nas inter-relações com aspectos reprodutivos. Os tratamentos utilizados foram: Controle (TC) dieta controle; Flushing (TF), dieta controle mais 300 g de fubá de milho; Flushing com nível 1 de própolis (TFP1), TF mais 8 mL de solução alcoólica de própolis/animal/dia; Flushing com nível 2 de própolis (TFP2), TF mais 12 mL de solução alcoólica de própolis/animal/dia. Foram utilizadas 16 fêmeas nulíparas vazias, sendo quatro por tratamento, distribuídas em experimento inteiramente casualizado, submetidas a um protocolo de sincronização de cio e posteriormente cobertas. Os animais foram estabulados por um período de adaptação de 10 dias, seguido de 30 dias de período experimental e alimentados duas vezes ao dia, às sete e 16 horas. Para determinar o perfil hematobioquímico, amostras de sangue foram coletadas a cada cinco dias, sendo a primeira coleta realizada com os animais em jejum e a segunda, duas horas após a alimentação das sete horas da manhã, durante 15 dias na fase pré cobrição e 15 dias na pós cobrição, para estimar os teores de ureia, proteínas totais, albumina, globulinas e a enzima AST. Utilizou-se ultrassonografia para confirmação de prenhez trinta dias após cobrição. Verificou-se que o tratamento com menor concentração de extrato etanólico de própolis Verde Alecrim apresentou potencial para diminuir consumo de MS e que o extrato etanólico de própolis demonstrou ser eficiente na diminuição do consumo de matéria seca e na concentração de ureia sérica. Os tratamentos TC, TF e TFP1 apresentaram mesma taxa de prenhez, superior ao TFP2, contudo o TFP1 resultou em maior taxa de partos gemelares. O tratamento com menor concentração de própolis reduziu a concentração de ureia sérica nos momentos jejum e duas horas após alimentação e na fase pós cobrição. Os teores dos metabólitos, em sua maioria, encontram-se dentro dos limites de valores de referência
The aim of this research was to evaluate diets with and without inclusion of propolis ethanolic extract Verde Alecrim on dry matter intake, metabolic profile and its relationships of reproductive aspects and to compare metabolic profile values with reference values established on the scientific literature. Treatments were: Control (CT), control diet; Flushing (FT), control diet plus 300 g/animal/day of corn meal; Flushing with level 1 of propolis (FTP1), FT plus 8 mL/animal/day of propolis ethanolic extract; Flushing plus level 2 of propolis (FTP2), FT plus 12 mL/animal/day of propolis ethanolic extract. Sixteen Santa Inês nulliparous ewes, empty, four per treatment, were assigned in a complete randomized design, in a factorial scheme and subjected to an estrus synchronization protocol and covered. The females were housed and the experiment consisted of an adjustment period of ten days, followed by an experimental period of 30 days (15 days for pre-mating and 15 days for post mating). Animals were fed twice a day at 7 AM and 4 PM. To determine the hematobiochemical profile, blood samples were collected at each five days in fasting and two hours after during 15 days in the pre-mating phase and 15 days in the post mating to estimate urea, total protein, albumin, globulins and AST enzyme contents. Ultrasound to confirm pregnancy thirty days following mating was used. It was found that treatment with lower concentrations of propolis ethanol extract Verde Alecrim presented the potential to decrease DM intake intake and that the ethanol extract of propolis has proved effective in decreasing the dry matter intake and concentration of serum urea. The CT, FT and FP1T provided the same pregnancy rate, superior to TFP2, however FP1T resulted in higher rate of twin births. Treatments with a lower concentration of propolis reduced urea content in serum in fasting and two hours after feeding and in the post-mating phase. Most of metabolite contents were within reference values, according to the literature

CAPES
A análise genética é uma ferramenta que pode auxiliar na busca de melhores índices zootécnicos na ovinocultura leiteria. Há muitos anos as curvas de lactação e a estimação dos componentes de variância dos parâmetros calculados a partir delas, vêm sendo utilizadas nas estratégias de manejo em fazendas leiteiras, pois é possível alterar o formato da curva de lactação por meio da seleção. No Brasil, há uma grande lacuna sobre conhecimento técnico relacionado aos ovinos leiteiros no país. A estimação dos parâmetros da curva de lactação e posterior estimação dos componentes de variância permitem um melhor entendimento dos componentes genético e ambiental que afetam a produção, antecipando as informações necessárias para a tomada de decisão sobre o direcionamento do manejo genético dos rebanhos. O objetivo do trabalho foi estimar os componentes de variância e os parâmetros genéticos dos componentes da curva de Wood em um rebanho de ovinos da raça Lacaune. Foram utilizadas 3558 informações de ovinos da raça Lacaune, e estimados os componentes de variância e os parâmetros genéticos dos parâmetros para a produção inicial (a), acréscimo até o pico (b), decréscimo após o pico (c), dia do pico (d), produção no pico (p), persistência (ln(s)) e produção total (y) da curva de Wood via estimação Bayesiana por meio do método de amostragem de Gibbs. A média estimada para os parâmetros a, b, c, d, p, ln(s) e y foram 0,362; 0,135; 0,032; 3,911; 1,703; 4,049; 76,249, respectivamente. As herdabilidades médias estimadas foram 0,41 (a), 0,47 (b), 0,50 (c), 0,11 (d), 0,30 (p), 0,36 (ln(s)) e 0,002 (y). As correlações fenotípicas e genéticas entre o parâmetro a e as demais variaram de -0,13 a 0,39 e -0,06 a 0,24, respectivamente. No parâmetro b variaram de - 0,002 a 0,17 e 0,04 a 0,15, parâmetro c de -0,01 a 0,11 e 0,04 a 0,10, parâmetro d de - 0,13 a 0,39 e -0,02 a 0,11, parâmetro p de -0,15 a 0,39 e -0,12 a 0,24, parâmetro ln(s) de -0,15 a 0,39 e -0,12 a 0,11, e para o parâmetro y variaram de -0,002 a 0,33 e 0,04 a 0,08. As repetibilidades identificadas foram 0,81 (a), 0,94 (b), 0,98 (c), 0,22 (d), 0,60 (p), 0,71 (ln(s)) e 0,003 (y). Conclui-se que as estimativas médias de herdabilidade e correlações identificadas evidenciaram um forte efeito ambiental afetando a expressão da característica produção de leite e baixas correlações genéticas entre os parâmetros da curva e a produção, indicando que a seleção pela produção de leite trará pouco ganho genético. Por outro lado, a seleção considerando todos os parâmetros da curva pode ser mais conveniente. Além disso, fica evidenciada a necessidade da padronização do manejo do rebanho. Devem ser elaborados estudos mais detalhados que permitam entender a relação dos parâmetros. O banco de dados pode ser trabalhado em outros períodos de lactação para um melhor conhecimento das estimativas dos componentes de variância. Seria de grande valia estudos sobre componentes principais e análise de trilha para posterior utilização no método de índice de seleção, para corroborar com a seleção que considera todos os parâmetros da curva.
Genetic analysis is a tool that can help in the search for better zootechnical indexes in dairy sheep breeding. For many years the lactation curves and the estimation of variance components of the parameters calculated from them have been used in management strategies in dairy farms since it is possible to change the shape of the lactation curve through selection. In Brazil, there is a large gap regarding technical knowledge related to dairy sheep in the country. The estimation of lactation curve parameters and subsequent estimation of the components of variance allow a better understanding of the genetic and environmental components that affect production, anticipating the information necessary for decision making on the direction of the genetic management of the herds. The aim of this work was to estimate the components of variance and the genetic parameters of the components of the Wood curve in a herd of Lacaune sheep. We used 3558 information from Lacaune sheep, and estimated the variance components and genetic parameters of the parameters for initial production (a), increase to peak (b), decrease after peak (c), peak day (d), peak production (p), persistence (ln (s)), and total production (y) of the Wood curve via Bayesian estimation using the Gibbs sampling method. The estimated mean for parameters a, b, c, d, p, ln (s) and y were 0.362, 0.135, 0.032, 3.911, 1.703, 4.049, 76.249, respectively. The estimated mean heritabilities were 0.41 (a), 0.47 (b), 0.50 (c), 0.11 (d), 0.30 (p), 0.36 (ln (s)) and 0.002 (y). The phenotypic and genetic correlations between parameter a and the others ranged from -0.13 to 0.39 and -0.06 to 0.24, respectively. In parameter b ranged from -0.002 to 0.17 and 0.04 to 0.15, parameter c of -0.01 to 0.11 and 0.04 to 0.10, parameter d of -0.13 to 0.39 and - 0.02 to 0.11, parameter p of -0.15 to 0.39 and -0.12 to 0.24, parameter ln (s) of -0.15 to 0.39 and -0.12 to 0.11, and for the parameter y ranged from -0.002 to 0.33 and 0.04 to 0.08. The repeatability identified were 0.81 (a), 0.94 (b), 0.98 (c), 0.22 (d), 0.60 (p), 0.71 (ln (s)) and 0.003 (y). It was concluded that the average estimates of heritability and correlations showed a strong environmental effect affecting the expression of the characteristic milk production and low genetic correlations between the parameters of the curve and the production, indicating that the selection by milk production will bring little genetic gain. On the other hand, the selection considering all parameters of the curve may be more convenient. In addition, the need for standardization of herd management is evidenced. More detailed studies should be developed to understand the relationship of the parameters. The database can be worked on in other lactation periods for a better understanding of the variance component estimates. It would be of great value studies on main components and track analysis for later use in the selection index method, to corroborate with the selection that considers all parameters of the curve.

Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: In terms of its contribution to the agricultural economic activity in Namibia, the small stock industry is the most important sector, second only to the beef industry. This sector makes a significant contribution to the agricultural business in Namibia due to the sector’s exports, its provision of employment, use of natural resources, contribution to GDP and to consumer spending as well as food security. Agricultural activities in Namibia contributed 5.5 percent to Namibia’s GDP, while 70 percent of the population relies on agriculture for employment and day-to-day living. Livestock farming in Namibia is free ranging on natural pastures and therefore produces high-quality meat that is in high demand in both the national and international markets. Small stock production in Namibia is unstable due to the high variability of weather patterns, changes in economic and social environments, unpredictable droughts as well as political and structural changes. Due to the decline in mutton production over the last years, research in the supply economics of the mutton industry in Namibia is important. The purpose of this study is to investigate the relationships between the various price and non-price factors contributing to the supply dynamics within the mutton industry in Namibia. Two hypotheses are tested with the aid of econometric modelling techniques on monthly time series data. The Autoregressive Distributed Lag approach to co-integration was used to determine the long-run and short-run supply response elasticities towards economic and climatology factors. Results showed a significant long-run relationship between the average Namibian mutton producer price and mutton supply. Results revealed that a one percent increase in the mutton producer price leads to a 1.97 percent increase in mutton supply. Beef producer price, a substitute product to mutton, showed a significant negative long-run effect towards mutton production whereas rainfall showed a meaningful positive long-run contribution to mutton supply. These supply shifters towards mutton production also showed significant short-run elasticities. Results further revealed that the system takes nearly two months to recover to the long-run supply equilibrium, should any disturbances occur within the supply system. The study showed that price-related and climatological factors play a major role in the Namibian mutton production industry. Industry stakeholders and policy makers should therefore incorporate these significant relationships between supply shifters and production output into future decisions and marketing policies to secure a healthy, growing and sustainable mutton industry in Namibia.
AFRIKAANSE OPSOMMING: In terme van bydrae tot die landboubedryf in Namibië is die kleinveebedryf die tweede belangrikste sektor, net kleiner as die land se grootveebedryf. Die sektor maak ‘n betekenisvolle bydrae tot die landboubedryf in Namibië deur middel van werkskepping, die gebruik van natuurlike hulpbronne, bydrae tot Bruto Binnelandse Produk, uitvoere, verbruikersbesteding sowel as voedselsekerheid. Landbou-aktiwiteite dra by tot 5,5 persent van die Bruto Binnelandse Produk van ‘n land waar meer as 70 persent van die bevolking afhanklik is van landbou om ‘n bestaan te kan maak. Veeboerdery in Namibië geskied ekstensief op natuurlike veld wat lei tot die produksie van ‘n hoë kwaliteit produk, wat hoog in aanvraag is in plaaslike en internasionale markte. Kleinvee produksie in Namibië is onstabiel as gevolg van fluktuasies in weerpatrone, veranderings in ekonomiese en sosiale omgewings, onvoorspelbare droogtes asook politieke- en struktuurveranderinge. As gevolg van die huidige afname in skaapvleis produksie is navorsing in die aanbodkantekonomie van die skaapvleisbedryf belangrik in Namibië. Die doel van hierdie studie is om die verwantskap te ondersoek tussen verskeie prys en nie-prys faktore wat bydra tot die aanboddinamika van die skaapvleisbedryf. Twee hipoteses word getoets met behulp van ekonometriese modelleringstegnieke op maandelikse tydreeksdata. ‘n Outoregressiewe verspreide sloeringbenadering tot ko-integrasie is gebruik om die langtermyn en korttermyn elastisiteite tussen ekonomiese en klimaatsfaktore vir die aanbod van skaapvleis te bepaal. Resultate dui op ‘n betekenisvolle langtermyn verwantskap tussen die gemiddelde Namibiese produsente prys en skaapvleis produksie. Resultate wys daarop dat ‘n een persent styging in skaapvleis produsente prys ‘n 1,97 persent styging in skaapvleis aanbod het. Die beesvleis produsente prys, ‘n substituut vir skaapvleis, het ‘n beduidende negatiewe effek getoon oor die langtermyn op skaapvleis produksie. Reënval het ‘n beduidende positiewe bydrae getoon ten opsigte van skaapvleis aanbod. Hierdie aanbodsfaktore het betekenisvolle korttermyn elastisiteite getoon. Resultate het ook getoon dat die stelsel twee maande neem om te herstel tot die langtermyn aanbodsewewig, sou daar enige drastiese veranderings in die stelsel plaasvind. Die studie het getoon dat prysverwante en klimaatsfaktore ‘n uiters prominente rol speel met betrekking tot skaapvleisproduksie in Namibië. Bedryfsaandeelhouers en politieke leiers sal hierdie betekenisvolle verwantskappe tussen produksie faktore en aanbod uitset in ag moet neem in toekomstige beplanning en bemarkingsbeleid om ‘n gesonde, groeiende en volhoubare skaapvleisbedryf in Namibië te verseker.

Les nématodes gastro-intestinaux sont l’une des contraintes majeures pour la santé des petits ruminants mis en pâture, entraînant de nombreuses pertes de production. Leur contrôle au moyen de traitements anthelminthiques est de moins en moins efficace à cause du développement de la résistance larvaire. De nombreuses recherches ont mené à l’étude de différentes stratégies complémentaires à l’utilisation massive de ces traitements chimiques : nutrition de l’hôte, gestion des pâtures, sélection génétique. Une approche de modélisation permet de simuler de multiples scénarios en minimisant l’effort expérimental, et notamment le recours à des infestations coûteuses en animaux, afin de trouver la meilleure stratégie de lutte intégrée du parasitisme. Le modèle épidémio-génétique précédemment développé par le Roslin Institute modélisant un troupeau d’agneaux en croissance infecté par le parasite T. circumcincta permet d’étudier l’impact d’une utilisation raisonnée des traitements, de la nutrition et de la résistance de l’hôte sur le niveau d’infection et de production du troupeau. Les travaux de la présente thèse consistaient à modifier ce modèle afin de modéliser des brebis adultes, notamment autour de la période d’agnelage où les besoins nutritionnels sont très importants. Cette modélisation a été complétée par la prise en compte du renouvellement d’un troupeau afin de considérer un troupeau durable, avec des accouplements, des réformes et des reproductions. Ainsi, notre modèle permet d’étudier les différentes stratégies de contrôle du parasite sur le long terme. Afin de s’assurer de la cohérence des sorties de cette modélisation avec des données réelles, le niveau d’infection a été comparé à celui de femelles infestées autour de l’agnelage. Cependant, comme de nombreux paramètres sont propres à la modélisation et donc non estimables à partir d’expérimentations, une analyse de sensibilité a aussi été mise en place pour dégager les paramètres qui contribuaient le plus à la variation du niveau d’infection. Parmi les parasites les plus fréquents chez le mouton, on trouve deux parasites majeurs T. circumcincta et H. contortus. Le parasite H. contortus est le plus virulent dans des climats chauds et humides, il nous paraissait donc utile de développer un nouveau modèle prenant en compte ce parasite. Préalablement, une méta-analyse des études utilisant des infections par le parasite H. contortus a été réalisée afin d’estimer les traits de vie du cycle parasitaire de ce parasite. Ces estimations ont ensuite été utilisées pour adapter le modèle épidémio-génétique à des infections par H. contortus. Cependant certains paramètres restent inconnus car ils ne sont pas estimables directement. C’est pourquoi nous avons réalisé l’estimation des trois paramètres inconnus principaux de notre modèle (précédemment soulignés par l’analyse de sensibilité sur T. circumcincta) en minimisant les écarts entre le niveau de charge parasitaire reportée dans une étude considérant des infestations successive par H. contortus ([25]) et nos simulations correspondantes. Dans cette thèse nous avons développé des modèles permettant d’évaluer sur le long terme les différentes stratégies de contrôle de deux nématodes gastro-intestinaux (T. circumcincta et H. contortus) dans les troupeaux ovins. Notamment, le modèle prenant en compte H. contortus pourra être utilisé pour prédire l’impact à l’échelle de l’élevage (nombre de traitements nécessaire, niveau d’infection des animaux) d’une sélection génétique sur la résistance au parasitisme dans une race. Les nématodes gastro-intestinaux sont l’une des contraintes majeures pour la santé des petits ruminants mis en pâture, entraînant de nombreuses pertes de production. Leur contrôle au moyen de traitements anthelminthiques est de moins en moins efficace à cause du développement de la résistance larvaire.
Gastro-intestinal parasitism is one of the most pervasive challenge for health and welfare in grazing small ruminants, leading to consequent production loss. Its control through the use of anthelminthic treatments is no longer sustainable due to the development of parasitic resistance to anthelmintics, but also due to environmental and consumer concerns. A substantial research effort proposed different supplementary control strategies to the massive use of anthelmintics: host nutrition, pasture management, breeding for resistance. Modelling approach allows for multiple scenarios to be considered without having to resort to experimentation in order to find the best integrated control strategies of parasitism. The epidemio-genetic model previously developed by the Roslin Institute modelling a growing lamb flock infected by the parasite T. circumcincta help to study the impact of rational use of anthelmintics, host nutrition and resistance on the flock level of infection and production. The researches of the current PhD thesis aimed to modify this model in order to add adult ewes modelling, especially around parturition where the nutritional requirements are very high. This modelling was improved by taking into account flock replacement in order to have a persistent flock with matings, reforms and reproductions. In this way, our model allows to study several control strategies of parasitism on long term perspective. In order to ensure adequacy of the model outputs to data, the infection level was compared to published data of ewes infected around parturition. However, some parameters were idiosyncratic to the modelling and then they were not be directly estimated from experiments. So a sensitivity analysis was also performed to highlight the parameters which mostly contribute to the infection level variations. Among the most prevalent parasites in sheep, T. circumcincta and H. contortus are the two main parasites. H. contortus is the most virulent parasite est le plus virulent parasite in hot and wet climates, so it is helpful to develop a similar model for this parasite. Beforehand, a meta-analysis of the published studies on infections with the H. contortus parasite was performed to estimate the main life history traits of its parasitic phase. Then, these estimations were used to change the epidemio-genetic model with H. contortus infections. However, some parameters remained unknown because they were not directly estimable. So, the three main unknown parameters (previously highlighted by the sensitivity analysis of the model with T. circumcincta infections) were estimated by minimizing the worm burden differences between published data of H. contortus trickle infection ([25]) and the corresponding model outputs. In this PhD thesis, models were developed in order to evaluate, in a long term perspective, several control strategies of two gastro-intestinal nematodes (T. circumcincta et H. contortus) infections in sheep flock. Notably, the model on H. contortus infections could be used to predict the impact of breeding for resistance to parasitism at the flock level (number of necessary treatments, infection level of the sheep)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Esse estudo teve como objetivo identificar e quantificar as diferenças na emissão de metano, consumo e digestibilidade aparente de ovinos mantidos em pastos de capim-massai (Panicum maximum x Panicum infestum) em sistema silvipastoril sob lotação intermitente com diferentes espaçamentos arbóreos. O experimento foi conduzido no setor de Forragicultura e Pastagens da FCAV, UNESP Jaboticabal, SP, no período de janeiro a julho de 2015. Os tratamentos foram constituídos de dois espaçamentos entre árvores de eucalipto (Eucalyptus urophylla x Eucalyptus grandis) (6,0m x 1,5m e 12,0m x 1,5m) em sistema silvipastoril (E6 e E12, respectivamente), e um tratamento que permaneceu sem árvores (SA). Foram utilizados ovinos adultos, manejados sob lotação intermitente. Como critério de entrada dos animais no pasto, foi utilizada a medida de 95% de interceptação luminosa do capim-massai. Como critério de saída, foi utilizada a altura de 20 cm da planta forrageira. O delineamento experimental foi inteiramente casualizado, com três tratamentos (arranjos arbóreos) e seis repetições (piquetes) no caso das variáveis de altura e massa do capim-massai e cinco repetições (animais) das variáveis de digestibilidade, consumo e emissão de metano (CH4). Os pastos foram avaliados em épocas do ano (águas e seca). Foi realizada a análise de contrastes ortogonais (1º e 2º graus) para os ciclos de pastejo e teste de médias Tukey para espaçamentos arbóreos (α=5%). Houve diferença significativa (p<0,05) entre os tratamentos para altura do dossel forrageiro, relação entre massa seca de forragem verde:morta e massa seca de forragem do pré e pós pastejo nos três ciclos, sendo o tratamento E6 o que apresentou os menores (p<0,05) valores em relação aos demais tratamentos. Houve interação significativa (p<0,05) entre os ciclos de pastejo e espaçamentos arbóreos para as médias de digestibilidade aparente da matéria seca (DMS). As médias de DMS do ciclo de julho foram maiores (p<0,05) do que as do ciclo de março. No ciclo de julho as médias de DMS variaram entre os espaçamentos arbóreos sendo no tratamento SA maiores (p<0,05) que o tratamento E6. Houve interação significativa (p<0,05) entre os ciclos de pastejo e espaçamentos arbóreos para as médias de consumo de forragem e de energia. O consumo de matéria seca (CMS) foi maior no ciclo de pastejo de julho. Houve diferença significativa (p<0,05) entre os espaçamentos arbóreos somente nas médias de CMS, consumo de energia bruta (CEB) e consumo de energia digestível (CED) do ciclo de pastejo de julho, onde o tratamento SA apresentou maiores (p<0,05) médias em relação ao tratamento E6. Houve interação significativa (p<0,05) entre os ciclos de pastejo e espaçamentos arbóreos nas médias de emissão de CH4 pelos animais por dia e por ano (CH4dia e CH4ano). No ciclo de pastejo de julho, as médias de CH4dia e CH4ano foram maiores (p<0,05) em comparação com as médias de março. As variáveis de emissão de CH4 por unidade de consumo apresentaram diferenças significativas apenas para ciclo de pastejo, onde julho apresentou menores (p<0,05) valores de emissão e CH4 por kg de matéria seca consumida, por energia bruta consumida e por energia digestível consumida, quando comparado às emissões do ciclo de pastejo de março.
This study aimed to identify and quantify the differences in methane (CH4) emission, intake and apparent digestibility of sheep kept in massaigrass pastures (Panicum maximum x Panicum infestum) in silvopastoral system under intermittent stocking with different arboreal spacings. The experiment was conducted at the Forage and Pastures sector of FCAV, UNESP Jaboticabal, SP, from January to July 2015. The treatments consisted of two spacings between eucalyptus trees (Eucalyptus urophylla x Eucalyptus grandis) (6,0m x 1,5m and 12,0m x 1,5m) in silvopastoral system (E6 and E12, respectively), and a treatment that remained treeless (TL). Adult sheep, managed under intermittent stocking were used. As animals enter criteria in the pasture was used to measure 95% light interception of massaigrass. As exit criteria, it used the height of 20 cm of the forage plant. The experimental design was completely randomized with three treatments (arboreal arrangements) and six replicates (paddocks) in the case of height and mass variables of the massaigrass and 5 repetitions (animals) of digestibility variables, intake and emission of methane (CH4). The pastures were evaluated in a year (water and dry seasons). The analysis of orthogonal contrasts was held (1st and 2nd degree) for grazing cycles and Tukey test for arboreal spacings (α = 5%). There was a significant difference (p <0.05) between treatments for sward height, ratio of dry matter forage: dead, dry herbage mass of pre and post grazing in the three cycles, the E6 treatment which presented the lower (p <0.05) values than the other treatments. There was a significant interaction (p <0.05) between grazing cycles and arboreal spacings for the average apparent digestibility of dry matter (DDM). The average DDM July cycle were greater (p <0.05) than those of March cycle. In cycle July average DDM varied between arboreal spacings being larger TL treatment (p <0.05) than the E6 treatment. There was a significant interaction (p <0.05) between grazing cycles and arboreal spacings for the average forage and energy intake. The dry matter intake (DMI) was higher in July grazing cycle. There was a significant difference (p <0.05) between the arboreal spacings only in average DMI, gross energy intake (GEI) and digestible energy intake (DEI) of July grazing cycle, where treatment TL showed higher (p <0.05) averages for the E6 processing. There was a significant interaction (p <0.05) between cycles of grazing and arboreal spacings in average CH4 emission by animals per day and per year (CH4day and CH4year). In the grazing cycle of July, the average CH4day and CH4year were higher (p <0.05) compared with the averages for March. The CH4 emission variables per unit of intake showed significant differences only for grazing cycle, where July showed lower (p <0.05) emission and CH4 per kg of dry matter consumed by gross energy consumption and digestible energy consumed when compared to emissions of March grazing cycle.

The effects of sheep scab, (Psoroptes ovis infestation) on the welfare of sheep were studied. Flocks of sheep naturally infested with sheep scab and flocks of uninfested sheep, were studied before and after treatment with acaricides. A group of sheep, experimentally infested with Psoroptes ovis mites, were studied throughout the infestation. Behaviour was studied using focal and scan sampling techniques. Sheep scab resulted in increases in rubbing, scratching and biting. Rubbing and scratching in infested sheep were sometimes accompanied by non-functional mouthing, considered to be a stereotypy. Times spent grazing, cudding and idling were not affected by sheep scab, but the bout lengths of grazing and idling were reduced. The experimental group showed an increasing neutrophilia through the infestation, with erratic increases in eosinophil count and fibrinogen, while haemoglobin concentration and haematocrit decreased. Naturally infested flocks showed lymphopenia after treatment. Serum globulin concentrations increased through the infestation, with a concurrent decline in serum albumin. The serum globulin started to decline within one month after treatment. Some lactate dehydrogenase isoenyzme fractions increased during the infestation. Prolactin decreased and β- endorphin increased throughout the experimental infestation, although seasonal factors may have influenced these results. There was no change in pressure nociceptor threshold due to sheep scab. A questionnaire survey of sheep farmers suggested that sheep scab in Britain had increased in incidence and distribution over the last decade. The welfare of sheep infected with sheep scab and the control of sheep scab are discussed in the context of the experimental findings.