Dissertations / Theses on the topic 'Sheep - Management'

9 pp.
As a general rule, lambs are not purchased until they are at least 8 weeks old and exceed 40lbs. in weight. The lamb should gain an average of .5 to .8 lbs. a day. This publication discusses how to feed a show lamb according to its nutrient needs.

Thesis (M.S.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains vi, 90 p. : ill. Vita. Includes abstract. Includes bibliographical references (p. 71-76).

This thesis presents an Actor-Network Theory (ANT) inspired analysis of sheep scab in Scotland. Sheep scab is caused by scab mites, and it has a long history in terms of its legislation and available treatments in the UK. In 2010 it became a notifiable livestock disease again in Scotland. Even though sheep scab is studied by natural scientists and economists, it remains unclear how scab is understood by sheep practitioners. This means that the stories, practices and knowledges of sheep practitioners who work at the forefront of sheep scab (in terms of its recognition, diagnosis, treatment and notification) remain absent from the political arena. However, their activities shape how rules and regulations are used. An ANT approach proved helpful for this research, because it allows the researcher to follow connections. The connections followed are sheep scab stories and practices. This research therefore has the following main question: How are multiple sheep scab situations enacted in Scotland? Multi-sited ethnography is the methodology used for this research, and semi structured interviews and field observations were done to get in-depth information about sheep scab situations in Scotland. In total 47 interviews, and 14 observations were done from 2013-2014 with diverse respondents ranging from farmers, veterinarians, slaughterhouse employees and natural scientists. This thesis contributes empirically and theoretically to human-animal studies (HAS). The empirical findings are that the notification legislation for sheep scab is rarely used; sheep scab diagnoses are rarely done; and finally, sheep practitioners trust their own situated knowledges of sheep scab. The theoretical contribution is a reworking of ANT to make it more suitable for studying sheep scab. In particular I rework ANT's confusing terminology; its tendency to reduce entities to their effects; and I include concepts from livestock disease literature that proved particularly helpful.

Domestic sheep farmers in the lower Fraser Valley (L.F.V.) had reported increasing losses of sheep to coyote (Canis latrans) and dog (C. familiaris) predation. The objectives of this study were: (1) to determine if management and geographic factors predispose sheep farms to coyote and dog predation; (2) to assess the relative impact of coyote and dog predation on the L.F.V. sheep population; (3) to record basic attributes of coyote biology (taxonomy, reproduction, food habits, home range, movements, activity patterns, and predatory behaviour); (4) to provide practical and economical recommendations to reduce or prevent coyote and dog predation on sheep in the L.F.V. One hundred and twelve sheep farmers were interviewed over three years, 1979 to 1981. Farms which lost sheep to coyotes characteristically had relatively large flocks (>50 ewes) on large fields (4+ ha), did not confine sheep at night, and either buried or left sheep carcasses exposed. There were no common factors among farms which lost sheep to dogs. Predation accounted for 28.2% of all mortality and 2.4% of the total population sampled. Coyotes killed 69.7% and 74.7% of all ewes and lambs lost to predators. An average of 24.3% of the farms lost sheep to coyotes and dogs each year. However, 55.2% of the farms which lost sheep to coyotes did so in two or three consecutive years compared to 17.4% of farms which lost sheep to dogs. Coyotes in the L.F.V. were similar in most biological aspects studied to other coyote populations in North America. The only exception was that small rodents, primarily Microtus townsendi composed over 70% (scat volume) of their diet, a proportion higher than in other areas. Domestic livestock (mostly poultry carrion) comprised only 4.3% of the diet, sheep only 0.2%. I concluded that in the rural-urban L.F.V. interface, prevention of coyote predation (and secondarily dog predation) on hobby farms is largely a matter of management. The most effective and economical solution is to provide predator-proof enclosures for night confinement of sheep because coyotes were most active at night. This method could be further enhanced by removing livestock carcasses off the farm or by burying and liming them to avoid attracting coyotes to the farm vicinity.
Land and Food Systems, Faculty of
Graduate

Seventeen cougars (Felis concolor) utilizing the Junction Wildlife Management Area (W.M.A.) in central British Columbia were fitted with radio collars. All collared cougars within the area were relocated using ground-based and aerial radio telemetry. Relocations were made daily during intensive field work (December-August), and a minimum of four per week the remainder of the year. General site reconnaissance and direct sampling work from 1986 to 1988 revealed 132 prey species mortalities of which 50 were confirmed as recent cougar kills. Although bighorn ewes and lambs (Ovis canadensis californiana) were not important prey items for the cougars, bighorn rams comprised 77.6% of the total mortality sample and 46.5% of the confirmed cougar kills. Cougars selected rams in greater proportion than would be expected based on the availability of rams in the prey population. Poor post-rut body condition and restricted rear and peripheral vision were factors that increased the rams' vulnerability to cougar predation. Cougar predation rates on bighorn sheep and mule deer (Odocoileus hemionus hemionus) were determined for two females with kittens. Kill rates varied from 0.7 - 3.0 ungulates/week. Interactions between cougars and coyotes (Canis latrans) at kill sites influenced the cougars' utilization of kills and predation rates. In 200 km² of the 425 km² study area, 130 coyotes were removed over a two-year period. The predation rate of a cougar with three kittens within the coyote removal area averaged 1.1 kills/week while that of a female with two similarly-aged kittens in the non-removal area averaged 2.6 kills/week. Moreover, observations of cougars abandoning kills following harassment by coyotes, suggested that cougar/coyote interactions were an important part of the system. Poor lamb recruitment and a decline in the number of mature rams in the Junction herd are a concern for the Ministry of Environment (MOE) Wildlife Branch. I make two recommendations that address these concerns: 1. Maintain the resident cougar population without removing cougars. Cougars were not important predators of the lamb segment, nor were cougars keying on the older, larger rams. Moreover, removal of the resident cougar population will disrupt the intraspecific and territorial dynamics of the cougar population resulting in an influx of transient cougars. This, in turn, will lead to the Junction system stabilizing at cougar numbers equal to or possibly greater than pre-removal levels. 2. Initiate an alternating, two-year on, two-year off, February-April coyote removal program until Iamb recruitment remains above 20 lambs/100 ewes throughout a four-year cycle. This program is preferable to cougar removal in that coyote removal can be implemented more effectively on a temporally and spatially scale. Coyote removal will result in an increase in lamb recruitment to the bighorn population, including the ram component. Moreover, fewer rams from this increased population will be killed because of lower cougar predation rates that also will result from the decrease in coyote scavenging/displacement pressures.
Science, Faculty of
Zoology, Department of
Graduate

Lamb survival and productivity from birth to weaning and lamb postweaning management harvest are areas that the US sheep industry needs to become more efficient at to remain profitable. Western white-faced ewes were supplemented HIGH (12.5% rumen by-pass protein, 880 IU/kg of supplemental Vitamin E, 176 ppm chelated Zn, and 72.7 mg/kg chlortetracycline) or LOW (7.56% rumen by-pass protein, with no supplemental Vitamin E, chelated Zn, or chlortetracycline) supplements at 0.227 kg•ewe -1•d -1 during late gestation. Ewes of different age and body condition scores were individually supplemented for 29 d prior to expected lambing. Thereafter, each ewe was mass fed the appropriate supplement until lambing. In Experiment 3, approximately 600 ewes were group fed HIGH or LOW supplements over 2 yr. Differences in antibody transfer from ewe to lamb were detected in supplemented ewes of different age (P < 0.10); however, lamb production was not different (P > 0.10) for all 3 experiments. To investigate lamb post-weaning management, terminally sired lambs (n = 72) were randomly assigned to 1 of 4 backgrounding treatments. Lamb backgrounding treatments were: ad libitum access to 80% alfalfa: 20% barley pellets (PELLET); cool season grass paddock grazing (GRASS); remain with ewe flock on fall dormant range (LATE WEAN); wean for 96 h and returned to ewe flock on dormant range (RANGE). Background treatments were applied for 29 d. Thereafter, lambs were finished on a corn based diet. Lamb BW and ultrasound measurements were taken at weaning, after background treatment, after feedlot step-up and at the conclusion of the finishing period. Pen intake was measured. Lambs backgrounded on PELLET were heavier (P < 0.10) than all other treatments after the backgrounding period and at the end of the feedlot period. Lambs backgrounded on PELLET had the greatest intakes and ADG (P < 0.10) during the feedlot period. At beginning and end of the feedlot period, PELLET and GRASS lambs had larger (P < 0.05) LM areas than RANGE and LATE WEAN treated lambs. Under the condition of the studies, late gestational supplements did not improve ewe productivity and backgrounding treatments on dormant range diminished feedlot productivity.

The studies within this thesis have made a valuable contribution to our understanding of anthelmintic resistance in Scotland and in particular to the prevalence of benzimidazole (BZ) and ivermectin (IVM) resistance, the expression of multiple resistance and its management. Parasitic gastroenteritis (PGE) is a major welfare issue not only for Scottish, UK and European farmers but also for livestock producers throughout the world. Parasites such as Haemonchus, Trichostrongylus and Teladorsagia are estimated to cost the sheep industry hundreds of millions of dollars annually. To date control has largely been achieved using anthelmintics, but over reliance on anthelmintics has led to the development of multi class anthelmintic resistance (AR) and the realization that intensive chemoprophylaxis is not a sustainable approach for the control of nematodoses. The first two papers contributing to this thesis assessed the prevalence of benzimidazole (BZ) and ivermectin (IVM) resistance within ovine gastrointestinal nematode populations in Scotland. The prevalence of BZ resistance in selected Scottish lowland sheep farms was around 24% in 1991 but this had risen to over 80% by 2001. The first cases of ivermectin resistance in sheep were only detected in 2001 but a small scale survey in 2004 showed that 35% of the farms (6 from 17) surveyed had IVM resistance, with Teladorsagia and Trichostrongylus being identified as the resistant genera. The isolation of a triple class resistant T. circumcincta (MTci5) population has enabled research to focus on the important issue of the therapeutic and prophylactic management of this emerging problem. The third and fourth papers detail a series of controlled efficacy tests conducted on MTci5 that confirmed, in the short term at least, it should be possible to use a milbemycin (moxidectin; MOX) or combination treatments, with IVM and one other class of anthelmintic to control nematodoses (>90% efficacy) caused by adult and/or immature worms. However the study examining larval susceptibility highlighted the important role that immature stages can play in the selection and transmission of resistance. Currently there are no tests that can detect the presence of these resistant larval stages. The fifth paper outlines parasitological findings from the farm where MTci5 was isolated following the confirmation of multiple class resistance. Substantial efforts were made to find solutions to maintain sustainability and profitability of the enterprise though ultimately the use of MOX selected for a, predominately Teladorsagia, population against which the persistent activity of the compound was only negligible with the reappearance of eggs in faeces occurring between 21 and 28 days post treatment. Effective sustainable control of AR populations not only requires an understanding of the phenotypic and genotypic mechanisms that underpin resistance but also improved means of ensuring that our farmers are made aware of and utilize identified best practice approaches. The written and verbal responses of the farmers to questions relating to best practice advice (papers six and seven) would suggest that many of the recommendations for delaying the selection and transmission of AR (ACME, Moredun Foundation and sustainable control of parasites of sheep (SCOPS), DEFRA) are not being followed, recommendations such as the effective quarantine treatment of newly purchased animals and dosing animals at the manufacturers’ recommended dose rate were followed by only 20% and 56% of farmers respectively.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior
O objetivo deste estudo foi o de determinar o desempenho reprodutivo de ovelhas Santa InÃs, mantidas em trÃs modelos de produÃÃo visando determinar a influÃncia do grau tecnolÃgico na reproduÃÃo dos animais. Durante trÃs anos foram avaliadas 150 ovelhas divididas no inicio do experimento em trÃs grupos homogÃneos quanto à idade e peso corporal, sendo cada grupo submetido a trÃs modelos de produÃÃo diferente. No Modelo 1 as ovelhas foram acasaladas trÃs vezes em dois anos, mantidos em pastagem nativa (caatinga) durante o acasalamento (Ãpoca chuvosa) e em pastagem cultivada (Ãpoca seca) durante o perÃodo do terÃo final da gestaÃÃo atà o acasalamento seguinte. No Modelo 2, as ovelhas foram acasaladas uma vez ao ano com repetiÃÃo de cobertura, cinco meses apÃs a primeira, mantidas em pastagem nativa antes, durante e apÃs o acasalamento (Ãpoca chuvosa) e em pastagem cultivada durante o perÃodo final de gestaÃÃo e a lactaÃÃo (Ãpoca seca). No Modelo 3, as ovelhas foram acasaladas uma vez ao ano, e mantidas exclusivamente em pastagem nativa, com suplementaÃÃo na forma de feno no perÃodo seco. Todos os animais receberam suplementaÃÃo mineral ao longo do perÃodo experimental. Houve influÃncia significativa do modelo de produÃÃo e do ano de observaÃÃo nos pesos corporais das matrizes ao acasalamento, pariÃÃo e desmame e Ãndices calculados, com valores significativamente superiores no Modelo 1 e no ano de 2008. Conclui-se que o nÃvel tecnolÃgico influi significativamente no peso corporal e nos parÃmetros reprodutivos de ovelhas na regiÃo semi-Ãrida do Brasil, sendo viÃvel trÃs pariÃÃes em dois anos.
The objective of this study was to determine the reproductive performance of Santa InÃs ewes maintained in three production models to determine the influence of the technological level in the reproduction of animals. During three years 150 sheep were assessed before the treatment period divided into three equal groups according to age and body weight, each group being subjected to three different production models. In Model 1, ewes were mated three times in two years, maintained in native grassland (caatinga) during the mating season (rainy season) and pasture (dry season) during the third trimester of gestation until the next mating. In Model 2, ewes were mated once a year with repeat coverage, five months after the first, kept on native pasture before, during and after the mating season (rainy season) and cultivated pasture during late gestation and lactation (dry season). In Model 3, ewes were mated once a year and kept on native pasture with supplementation in the form of hay in the dry season. All animals received mineral supplementation throughout the experimental period. Significantly influence the production model and year of observation in the body weights of the sheep at mating, calving and weaning rates and calculated, with values significantly higher than in Model 1 and in year 2008. It is concluded that the technological level has a major influence on body weight and reproductive performance of sheep in semi-arid region of Brazil, with three viable calving at two years.

TEIXEIRA, Marcílio Costa. Utilização de três modelos de produção de carne ovina na região semi-árida do Brasil. 2010. 90 f. Tese (doutorado em Zootecnia)- Universidade Federal do Ceará, Fortaleza-CE, 2010.
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The objective of this study was to determine the reproductive performance of Santa Inês ewes maintained in three production models to determine the influence of the technological level in the reproduction of animals. During three years 150 sheep were assessed before the treatment period divided into three equal groups according to age and body weight, each group being subjected to three different production models. In Model 1, ewes were mated three times in two years, maintained in native grassland (caatinga) during the mating season (rainy season) and pasture (dry season) during the third trimester of gestation until the next mating. In Model 2, ewes were mated once a year with repeat coverage, five months after the first, kept on native pasture before, during and after the mating season (rainy season) and cultivated pasture during late gestation and lactation (dry season). In Model 3, ewes were mated once a year and kept on native pasture with supplementation in the form of hay in the dry season. All animals received mineral supplementation throughout the experimental period. Significantly influence the production model and year of observation in the body weights of the sheep at mating, calving and weaning rates and calculated, with values significantly higher than in Model 1 and in year 2008. It is concluded that the technological level has a major influence on body weight and reproductive performance of sheep in semi-arid region of Brazil, with three viable calving at two years.
O objetivo deste estudo foi o de determinar o desempenho reprodutivo de ovelhas Santa Inês, mantidas em três modelos de produção visando determinar a influência do grau tecnológico na reprodução dos animais. Durante três anos foram avaliadas 150 ovelhas divididas no inicio do experimento em três grupos homogêneos quanto à idade e peso corporal, sendo cada grupo submetido a três modelos de produção diferente. No Modelo 1 as ovelhas foram acasaladas três vezes em dois anos, mantidos em pastagem nativa (caatinga) durante o acasalamento (época chuvosa) e em pastagem cultivada (época seca) durante o período do terço final da gestação até o acasalamento seguinte. No Modelo 2, as ovelhas foram acasaladas uma vez ao ano com repetição de cobertura, cinco meses após a primeira, mantidas em pastagem nativa antes, durante e após o acasalamento (época chuvosa) e em pastagem cultivada durante o período final de gestação e a lactação (época seca). No Modelo 3, as ovelhas foram acasaladas uma vez ao ano, e mantidas exclusivamente em pastagem nativa, com suplementação na forma de feno no período seco. Todos os animais receberam suplementação mineral ao longo do período experimental. Houve influência significativa do modelo de produção e do ano de observação nos pesos corporais das matrizes ao acasalamento, parição e desmame e índices calculados, com valores significativamente superiores no Modelo 1 e no ano de 2008. Conclui-se que o nível tecnológico influi significativamente no peso corporal e nos parâmetros reprodutivos de ovelhas na região semi-árida do Brasil, sendo viável três parições em dois anos.

The main objectives of this study can be divided into three categories. In the first place it refers to the determination of production- and reproduction norms for the different main production areas in the greater Burgersdorp area, to promote production. In the second place it refers to the determination of the different management styles of sheep farmers in the greater Burgersdorp area. In the third place it refers to the calculation of gross margins for sheep farming in the greater Burgersdorp area, to establish the sustainable economic position. The survey area (the greater Burgersdorp area) includes the magisterial districts of Burgersdorp, Molteno, Steynsburg and Venterstad. The four magisterial districts were divided into two main production areas namely Stormberg Highveld and Burgersdorp Lowveld. Stormberg Highveld includes Molteno and the high-lying area (highveld) of Burgersdorp. Burgersdorp Lowveld comprises Steynsburg, Venterstad and the low-lying area (lowveld) of Burgersdorp. The management strategies of sheep farmers in the survey area were determined by means of a questionnaire and statistically analysed. The economic analyses of the sheep industry (wool and meat) were performed with the Geyer computer model. In this study it showed that the Dorper farmers obtained the highest gross margin per sheep. The lowest gross margin per sheep resulted from the Vleismerino farmers. Although the composition of the gross production value and the directly allocatable variable costs compare favourably, each main production area has unique management strategies for the different sheep breeds. The different management strategies can serve as the norm for extensive sheep farming, applicable to the specific main production area.

Master of Science
Department of Agronomy
Peter J. Tomlinson
In recent years, an alternative grazing method to continuous and rotational methods has gained popularity among producers and has been termed mob grazing. Mob grazing uses high animal densities grazing for a short period of time. The objectives of this study were to determine the impact of continuous, rotational, and mob grazing on forage production and the quality of smooth bromegrass (Bromus inermis Leyss), along with soil dissolved organic carbon (DOC), microbial biomass carbon (MBC), and dehydrogenase enzyme activity. Twelve paddocks, 4 continuous (40 X 10 m), 4 rotational and 4 mob (15 X 10 m), were designated at the Kansas State University Sheep and Meat Goat Center in Manhattan, KS. Forage quality samples were collected by hand clipping randomly throughout the paddock. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were determined using ANKOM technology and crude protein (CP) content was calculated by multiplying total nitrogen determined by combustion by 6.25. Soil samples were extracted with 0.5 M K2SO4 and analyzed for DOC and MBC using the chloroform-fumigation-extraction method and soil dehydrogenase activity using the colorimetric method. Forage quality declined as the spring grazing season progressed in all treatments. Sheep grazed higher quality forage in the continuous and rotational treatments in the period prior to the spring mob grazing event. No treatment differences were found for DOC, MBC, dehydrogenase, or total forage biomass accumulation. Dissolved organic carbon and soil biological parameters have not been altered by the grazing management. Forage quality was found to be poorest in the mob treatment at the time of grazing. The mob treatment accumulated the greatest amount of aboveground biomass prior to grazing, however season-long total biomass accumulation was not different from the other treatments. Based on this research, in the short-term, there are no advantages of mob grazing over rotational grazing.

Thesis (MPhil (Agricultural Economics))--University of Stellenbosch, 2005.
The Dorper Sheep species are exclusively bred for the dry arid conditions of some parts of South Africa. This species adapts easily and a prime lamb with great characteristics can be produced. There are two very important controlable factors regarding Dorper sheep farming namely herd management and cultivation. Herd management involves feeding, mating, mating methods and the handling of animals and their products. A few good objectives of herd management are the short breeding interval, low deaths and high performance rating. Genetic improvement can be achieved by using good rams, the selection of ewe-lambs as forthcoming breeding ewes, culling of uneconomic producers and the application of good breeding practices to improve meat production and reproduction. In this study a comparison is made between the management practices (herd management and cultivation) of Dorper farmers in 1990 and the management practices of Dorper farmers in 2004. For this aim the research of J.J. Ackermann (1990) was used. In 2004 questionnaires were send to Dorper farmers throughout South-Africa to get more information about their management practices. The conclusion of the study was that there was an increase in tertiary qualification of Dorper farmers from 1990 to 2004 and that more farmers used modern practices instead of the old traditional methods.

Involving a diversity of stakeholders in conservation issues is an important and growing trend in wildlife management. My thesis provides a case study of a collaborative conservation effort in which representatives from sportsmen’s and environmental groups came together to advise the Arizona Game and Fish Department in a project to restore bighorn sheep to the Santa Catalina Mountains near Tucson, Arizona. These stakeholders formed the Catalina Bighorn Sheep Restoration Advisory Committee to help address the human dimension factors of the project, build public support, and guide project planning and implementation. In addition to participant observation and document analysis informing my study, I surveyed 31 stakeholders both on and off the Advisory Committee and interviewed key Advisory Committee members. All stakeholders were in favor of collaborative conservation. However, there were objections to this particular Advisory Committee for this particular project. Although stakeholders had a diversity of values that informed their beliefs, the Advisory Committee members who took the time to understand the science involved, develop mutual trust and respect for others at the table, and held a strong commitment to the project goals were able to shift deeply held, values-based beliefs and find consensus on contentious project elements. This included agreeing on a mountain lion management plan that called for the killing of mountain lions that preyed on the newly reintroduced bighorn sheep. Stakeholders not on the Advisory Committee did not come to agreement on most elements of the project. This study contributes to the understanding of collaborative conservation efforts by providing a case study of a controversial wildlife conservation project that involved diverse stakeholders who worked together, successfully found consensus, and achieved their main goal of getting bighorn sheep back on the mountain.

Data generated by five years of FAMACHA© clinical evaluation trials on one farm, and two years of trials on a second farm in South Africa, where targeted selective treatment was applied to treat haemonchosis in sheep, was used as a basis to explore new computational epidemiological methods to analyse the results of the trials. The research flowed from the earlier work of Dr. J.A. van Wyk and co-workers at the Faculty of Veterinary Science, University of Pretoria, who did much to develop, introduce, and validate the FAMACHA©system in South Africa and elsewhere in the world. Clinical haemonchosis was common during the summer rainfall season, and was found to increase in severity during January and February of each year. Sensitivity analysis of FAMACHA© data indicated that on the first farm (Farm 1) investigated, many of the animals that were clinically non-diseased were in fact anaemic, but due to misclassification, these animals were not detected. This was not the case on the second farm (Farm 2), where most animals that were clinically diseased according to FAMACHA© were found to be truly anaemic. The high prevalence of misclassification on Farm 1 has important implications for monitoring and chemotherapy of haemonchosis. The results indicated that under the conditions where the data were generated, the FAMACHA© system is sensitive enough, and adequately specific, to detect anaemic sheep despite misclassification. The application of Receiver Operating Characteristic curve analysis to the FAMACHA© method to select FAMACHA© categories for treatment, was in agreement with the findings that misclassification on Farm 1 would of necessity require that different treatment thresholds would need to be implemented to achieve the same test sensitivity as on Farm 2.Although the use of the Receiver Operating Characteristic method requires the use of dedicated software to generate results, especially if large data sets are analysed, it was found to be an accurate and valid way of indicating FAMACHA© threshold categories for treatment on both farms, for a desired sensitivity. A previously published multiple regression model was modified to incorporate stochasticity in the FAMACHA© proportions and the body mass of sheep, in order to simulate probable worm count. The fluctuations in simulated worm count adequately reflected the changing epidemiological situation of haemonchosis as indicated by temporal histograms of differential FAMACHA© proportions in flocks. The model was most sensitive to changes in FAMACHA© proportions in the sample, followed by increasing variability in body mass as a worm season progressed. Furthermore, for a given class of animal, a range of probable haemoglobin values could be associated with a preselected threshold worm burden. Themodel was sensitive to blanket drenching events, as a lower intensity of infection was predicted immediately after blanket drenching in all samples. It followed that model indications could be used probabilistically, to indicate minimum haemoglobin levels that would need to be sustained in order to prevent overwhelming worm burdens in a given classof animal. The penultimate chapter of the thesis is concerned with alternative methods of evaluation of rainfall as a risk factor for haemonchosis. Three different periods of rainfall, in relation to FAMACHA© sampling events, were evaluated in terms of entropy, or spread, and tested for strength of association with simulated flock haemoglobin values by regression analysis. Shannon’s entropy was used as an indicator of rainfall variability. Findings indicated a negative, and significant, correlation between rainfall entropy and flock haemoglobin level. On the strength of the association, a simulation model was proposed, which could theoretically indicate a probable range for expected flock haemoglobin level in a subsequent two-week period following FAMACHA© evaluation, provided that rainfall entropy is known. This work attempts to bridge the gap between implementation of the FAMACHA© system, and the investigation of several vital issues that would need to be addressed in the development of a wider ranging anthelmintic treatment decision-support system to delay anthelmintic resistance. The application of important quantitative methods, such as two-graph Receiver Operating Characteristic analysis, Monte Carlo simulation, and Shannon’s entropy to the FAMACHA© system, have provided new perspectives from which to develop an integrated computerized decision-support system. The thesis strongly supports the continued use of the FAMACHA© system in its present form, but the work has emphasised several key issues, such as misclassification, the need to develop decision-support systems that are useable in real time at farm level as opposed to regional level, and that the FAMACHA© system can and should be used as a basis for further development of decision-support software.
Thesis (PhD (Veterinary Tropical Diseases))--University of Pretoria, 2007.
Veterinary Tropical Diseases
unrestricted

The rapid increase in the magnitude of anthelmintic resistance towards commercial chemical anthelmintics, calls for alternative methods to complement treatment or replace anthelmintics. During the last two decades more and more calls have been made for a holistic management solution. Recent studies on breeding for resistant animals and bioactive forages highlight the potential of these to contribute towards parasite control. For this study, gastrointestinal infection in a merino flock was investigated by means of faecal egg counts (FEC). The level of parasite infection in weaned merino lambs in their first summer could be linked to weather conditions. Anthelmintic resistance in the flock was quantified and compared to the resistance level some years earlier. Within the flock, 18% of the ewes appeared to be resistant with consistently (P<0.05) lower FEC than the rest of the flock. Lespedeza cuneata, a tannin-containing legume, is, according to scientific literature, one of the promising bioactive forages. Depending on the level of condensed tannin (CT), ruminant digestion can be complemented or compromised by the tannins. Small plot trials were conducted to establish production criteria for L. cuneata, currently lacking in South Africa. The grand mean dry mass (DM) yield for the first growing season, (characterized by above normal rainfall), was 8.3 t ha-1, compared to the 2.56 t ha-1 for the second growing season, (characterized by below normal rainfall). Highly significant differences (P<0.001) were measured between the yields produced under different cutting frequencies (6, 8 and 12 weeks) and cutting heights (5 cm and 15 cm). Except for crude protein levels, ADF (acid detergent fibre) and NDF (neutral detergent fibre) analysis of the complete plant indicated a less acceptable nutritional quality. Since sheep selected leaves during grazing, separated leaf samples were analysed. Chemical feed analyses of leaves were more favourable, compared to feed analysis of the whole plant. The condensed tannin (CT) content of leaves increased significantly (P<0.05) with increased moisture stress and varied between 24.5 and 122 g kg-1 DM over the growing seasons. Different dried herbage diets were offered to Merino ewes in a follow-up trial to evaluate the anthelmintic properties of the forage. The leaf portion of Lespedeza cuneata hay and Medicago sativa hay was offered ad libitum to confined sheep. Lespedeza cuneata is a tannin rich legume, while Medicago sativa, known for its very low tannin content, was used as control. FEC were significantly (P<0.05) lower in the Lespedeza group after 35 days. To determine the influence of condensed tannin (CT) level on the hatch efficacy of Haemonchus contortus eggs, acetone leaf extracts of L. cuneata plants with different condensed tannin contents (73.5, 88, 102 and 122 g kg-1 DM) were tested in an in vitro assay on H. contortus eggs. Concentrations of between 0.63 and 20 mg ml-1 were used in the assay. Concentrations higher than 10 mg ml-1 led to complete inhibition of egg hatching with all the plant extracts regardless of CT content. A typical dose related response of the extracts of plants with very high tannin content was found, but not with plant extracts containing lower tannin concentrations. The results of the study indicate that L. cuneata can be incorporated in a fodder flow programme as an alternative or complementary strategy to other methods, to manage the detrimental effect of gastrointestinal parasites in sheep.
Dissertation (MSc)--University of Pretoria, 2014.
tm2015
Paraclinical Sciences
MSc
Unrestricted

The research was conducted in the Hewu area situated between Queenstown (20 km) and Whittlesea (15km) in the Eastern Cape Province of South Africa. In this area communal farming is practiced. Livestock and livestock products (wool) are the main sources of income. The farmers are mainly farming with Merino and Döhne Merino sheep. The lack of management systems (production, reproduction and management) for communal farmers resulted into ineffective communal farming defining the research problem. The research objectives set were: • To establish production norms for wool sheep. • To establish reproduction norms for wool sheep. • To establish effective management practices for wool sheep farmers. • To examine key constraints of wool sheep farmers. The farmers shear their sheep every 12 months usually in October of every year. The average wool production per sheep is 2.17kg. The clip averages a fineness of 19.1-20 micron. That is far below the wool production of the commercial farmers of the Eastern Cape who are producing between 4kg to 5kg per sheep at an average growing period of 12 months. The lack of proper fencing and camps causes major reproduction problems. The lambing percentage of the ewes is 94.85 percent. The weaning percentage referring to the reproductive efficiency of the mated ewes is only 17.24 percent. The survival rate of the lambs born alive is only 18.18 percent. Reproduction is the biggest problem of communal farms. Effective livestock- and grazing management systems for communal areas are essential for the successful development of farmers on communal grazing areas. Unfortunately the Hewu farmers still have many problems effecting their wool production and the production of lambs.

Diet selection and self-medication are fundamental to the survival of all species. The abilities to choose healthy foods in response to past consequences are basic elements of evolution. This study explores self-medication regarding tannins both as a medication and as a dietary challenge. In the first study, sheep with natural parasite infections were offered a low quality supplement containing a dose of tannins considered to be therapeutic (medicine), while the control infected lambs received the same supplement without tannins (placebo). This study included a group of parasite-free lambs. The parasitized lambs ate more of the tannin containing supplement than non-parasitized lambs for the first 12 d of the study, when parasite burdens were high, but differences became smaller and disappeared towards the end of the study when parasite burdens decreased. This result indicated lambs ability to detect the presence of internal parasites and to learn to ingest tannin when followed by relief from parasite burdens.In the second study, lambs grazed on pastures with forages containing saponins (alfalfa),iiialkaloids (endophyte-infected tall fescue) and tannins (birdsfoot trefoil). I observed the foraging behavior of groups of lambs after intra-ruminal infusions of tannins (treatment). Lambs that first received intraruminal infusions of tannins and then were offered 2-way choices between varieties of forages with high and low concentrations of either saponins, alkaloids, or tannins increased their preference for the high-saponin variety of alfalfa and the high-alkaloid variety of tall fescue relative to lambs not infused with tannins (controls). Lambs infused with tannins and offered choices among the 3 forages with high concentrations of secondary compounds also manifested higher preference for the high-alkaloid variety of tall fescue than control lambs. In contrast, lambs infused with tannin reduced their preference for the high-tannin variety of birdsfoot trefoil.This research has implications for many situations where forages with secondary compounds are available but underutilized. Landscapes where such forages are available could be used effectively with little or no harm to livestock if medicinal forages or supplements are made available and offered as alternatives so animals can learn about their benefits of chemical complementarities among different plant species.

One of the major constraints limiting the efficiency of sheep production is the control of gastrointestinal nematode parasites. Parasite control by strategic use of anthelmintics is threatened by the emergence of nematode populations that are resistant to the drugs available. It is therefore increasingly apparent that steps toward maintaining sustainable productivity in the growing face of anthelmintic resistance (AR) is required by farmers. To facilitate the uptake of sustainable approaches to parasite management, a comprehensive understanding of the various factors that may influence farmers’ decision-making processes is required. In order to establish which factors are influential, and determine their impact on farmers’ roundworm control behaviours, both qualitative and quantitative research methods were used including focus groups as well as attitudinal and behavioural questionnaires. A retrospective analysis was initially conducted of historical surveys designed to identify farm specific characteristics and parasite management practices including anthelmintic usage. The objectives of the analysis were to identify factors associated with uptake of best practice advice including farm characteristics and information sourcing. In addition, the implementation of sustainable roundworm control practices was investigated using two surveys conducted in 2000 and 2010. Logistic regression models were applied for univariable and multivariable analysis of dependent and independent variables. The next step was to conduct a series of focus groups in different geographic regions of Scotland. The main purposes were to explore sheep farmers’ attitudes towards different aspects of roundworm management, as well as to identify potential motivators and barriers to uptake of sustainable parasite control practices. The findings aided in the development of an attitudinal questionnaire used to canvass opinions representative on a national level. The concluding study involved a telephone survey of 400 Scottish sheep farmers, designed to elicit attitudes regarding roundworm control, AR and sustainable roundworm control practices. A quantitative statistical analysis technique (Structural Equation Modelling) was then used to test the relationships between socio-psychological factors and the uptake of sustainable roundworm control practices. The analysis of historical questionnaire data demonstrated evidence of a shift towards the use of practices to reduce the rate of AR development, most notably a decline in the practice of ‘dose and move’ as well as an overall reduction in treatment frequency. Statistical analysis identified significant associations between farm characteristics and specific treatment strategies. For example, larger farms were more likely to adopt a set treatment regimen (P=0.036), compared with smaller farms, which were more likely to treat based on clinical signs of infection (P=0.021). Sourcing of roundworm control information primarily from veterinarians was most associated with treatment timings with no parallels between time points. From the qualitative focus group studies conducted we identified four overarching themes impacting on sheep producers’ attitudes to roundworm control and best practice advice. These themes comprised: a lack of perceived need to change, the complexity of advice, the ease of implementation of recommended practices and the effectiveness of extension approaches. Additionally, the most important and implementable guidelines identified by sheep farmers were: ‘working out a roundworm control strategy with an advisor’ and ‘administering anthelmintics effectively’ with regard to correct drenching practice i.e. appropriate dosing, administration and drug storage procedures. These findings exhibited similarities with veterinarians’ rankings with also, ‘testing for AR’, ‘preserving susceptible parasites’ and ‘reducing dependence on anthelmintics’ receiving the lowest rankings for importance and implementability. The quantitative analysis from the attitudinal/behavioural questionnaire identified eleven factors with significant influences on the adoption of sustainable roundworm control practices. The key influences on overall adoption were farmers’ baseline understanding about roundworm control and self-reported confirmation of anthelmintic resistance in their flock. Additional positive influences included, positive attitudes to veterinary services, enterprise type and perceived risk of AR. Factors that were shown to have the greatest relative effects on individual parasite control practices included; the perceived resource requirements for implementing a quarantine strategy, farmers’ AR suspicions for instigating AR testing and the confirmation of AR for adopting faecal egg count monitoring. The findings have highlighted several factors which can influence sheep farmers’ decisions to reject or adopt recommended roundworm control practices. It is evident that the perceived complexity, lack of need and practicality of the current recommendations necessitates changes to how extension is designed and disseminated to farmers. The findings also suggest that improving farmers’ acceptance and uptake of diagnostic testing and improving underlying knowledge and awareness about nematode control is a significant target to influencing adoption of best practice behaviours. The importance of veterinarians as highly-trusted information resources validates the need for further engagement with veterinarians concerning sustainable parasite control approaches, to facilitate collaboration with farmers. The need for interaction between farmers and their advisors is key to resolving the issues raised to enable the necessary explanation, justification and execution of recommended practices to suit farmers’ needs and farming conditions.

Two consecutive experiments were conducted to test a hypothesis that mixed grazing outcome is influenced by the type of stocking system applied. The objective of both experiments was to investigate the influence of co-grazing with sheep on cattle liveweight gain (LWG) under continuous (C) and rotational (R) stocking, where sheep weekly liveweight change under the two stocking systems was kept similar. In experiment I nine yearling heifers (266 ± 4.5 kg liveweight) and 27 ewe hoggets (54±0.9 kg liveweight) were continuously stocked for 19 weeks on an irrigated perennial ryegrass-white clover pasture (2.95 ha) maintained at a sward surface height (SSH) of 5cm by adding or removing additional animals in a fixed ratio (1: 1 W⁰.⁷⁵ cattle:sheep). An equal area of pasture was rotationally stocked by a similar group of animals where they received a new area of pasture daily and also had access to the grazed area over the previous 2 days. The size of the new area provided daily was such that the weekly liveweight change of rotationally co-grazed sheep was equal to that of those continuously co-grazed with cattle. Similar groups of animals were used in the second experiment with additional group of 9 heifers grazed alone on C and R pastures. Liveweight of animals was recorded weekly and final fasted weight was determined after 24-hour total feed restriction. SSH on both treatment swards was recorded daily. There were three intake measurement periods spread over the trial period. Organic matter intake (OMI) was predicted from the ratio of N-alkanes in faeces and herbage. Diet composition was determined by dissecting oesophageal extrusa samples. Grazing behaviour (bite rates and grazing time) were also recorded. The mean SSH for C pasture was 5.1±0.09 cm. Overall pre- and post-grazing SSH for R pasture was 15.9 ±0.12 and 5.6 ±0.07 cm, respectively. As determined by the protocol average daily LWG of sheep was similar between C and R (147 (±5.8) vs 138 (±6.7) g day⁻¹; (P>0.05). In contrast, cattle continuously stocked with sheep grew 200 g day⁻¹ slower than those rotationally stocked with sheep (800 (±41.6) vs 1040 (±47.7) g day⁻¹, P<0.0l). R heifers achieved 30 kg higher final fasted liveweight than C heifers (350 vs 381 kg; P<0.01). Overall LWG per ha was also 6 % higher under R than C stocking (674 vs 634 kg ha⁻¹). The OMD of both sheep (73.5 vs 75.8 %) and cattle (75.8 vs 78.0 %) diets was similar under continuous and rotational stocking. There was no significant difference OMI data also concurred with the L WG data (Cattle: 7.94 vs 6.31 (±0.32) kg day⁻¹ (P<0.05); sheep: 1.40 vs 1.44 (±0.04) kg day⁻¹ for Rand C treatments, respectively). There was no difference in clover content of cattle diet under C and R treatments. C heifers had higher number of bites per minute than R heifers (62 vs 56; P<0.05). Proportion of heifers seen grazing (every 15-minute) during four 24-hour observations was greater on C than R pasture (0.44 vs 0.31 (±0.03); P<0.05). The similarity coefficient between sheep and cattle diet was 0.61 and 0.76 under C and R stocking, respectively. The lower daily LWG of C heifers was attributed to (a) the lower SSH under C than R stocking and/or (b) the inability of cattle to compete well with sheep where there is small, continual renewal of resources (C) in contrast to a large periodic renewal under R stocking. This experiment showed that the outcome of mixed gruing can be influenced by the stocking system chosen. But it was not possible to apportion the difference in LWG of cattle between mixed grazing per se and the difference in mean grazed sward height (5.1 for C vs 10.8 cm for R). A second experiment was conducted to determine the relative performance of cattle co-grazed with sheep (CS) and grazed alone (CA) under each stocking system. Hence, there were four treatments. CA- continuous stocking (CA-C), CS- continuous stocking (CS-C), CA- rotational stocking (CAR) and CS- rotational stocking (CS-R). A total area of 4.42 ha was allocated to each stocking system. Under C stocking, 2.95 ha (2/3) was assigned to CS-C and 1.47 ha (1/3) to CA-C, and SSH on both treatments was kept at 4 cm by adding or removing extra animals. Under R stocking, CA-R and CS-R grazed side by side separated by an electric fence. They were given a fresh area daily, the size of which was varied such that the weekly LW change of R sheep was equal to that of the C sheep. CA-R received one-third of the new area though the size was adjusted regularly to achieve the same post-grazing SSH with CS-R. Measurements included: weekly liveweight change, OMI (two periods) and diet composition (using N-alkanes). The mean SSH of CA-C and CS-C swards was 4.27 and 4.26 (±0.02) cm, respectively. CA-R and CS-R swards had mean pre-grazing SSH of 14.9 and 15.2 (±0.08) cm and post-grazing heights of 4.87 and 4.82 cm (±0.03), respectively. The proportion of areas infrequently grazed was higher for CA-C than CS-C swards (0.22 vs 0.17, respectively). C and R sheep daily LWG: 155 (±0.6) and 147 (±0.7) g, and OMI: 1.96 and 2.04 (±0.ll) kg, respectively, were not significantly different. They also had similar diet composition. In comparison, CS-C heifers grew only at 69 % of the daily LWG achieved by CS-R heifers (706 vs 1028 (±72) g; P<0.05). LWG of CA-C and CA-R was 916 and 1022 (±72) g day⁻¹, respectively. The difference in LWG between CS-R and CS-C (D₁) heifers was due to difference in mean sward height, stocking system and mixed grazing, while D₂ (difference in LWG between CA-R and CAC) was due to difference in mean sward height and stocking system. D₁-D₂ (the effect of stocking system on mixed grazing) was 216 g and made up 67 % of the total difference between CS-R and CS-C. There was a significant stocking system-species mixture interaction in the final fasted LW achieved by heifers. Final fasted LW was significantly lower for CS-C than CA-C heifers (283 vs 323 (±9.7) kg), but did not differ between CS-R and CA-R (332 vs 330 (±9.7) kg, respectively). The digestibility of diet OM was similar for both continuously and rotationally stocked sheep (84.4 vs 83.2 %, respectively). Cattle diet OMO was 76.5, 74.7, 79.4 and 77.8 for CA-C, CS-C, CA-R and CS-R respectively (P>0.05). Differences in OMI followed a similar pattern to daily LWG. Mean daily OMI was 8.98, 6.24, 8.80 and 9.45 (±0.40) kg for CA-C, CS-C, CA-R and CS-R, respectively. Clover content of the diet of CA-C heifers was three times higher than that of CS-C heifers (30.7 vs 10.4 % OM; P<0.05); there was no difference in clover content of diets of CS-R and CA-R heifers (21.5 vs 23.9 % OM, respectively). In both stocking systems LWG per ha was higher on CA than CS treatments. These results suggested that the disadvantage of selective clover grazing by sheep outweighed the advantages of sheep grazing around cattle dung patches under continuous stocking. Under rotational stocking, rapid diurnal changes in sward conditions probably limited selective grazing by both sheep and cattle such that there was no disadvantage to CS cattle. The results do not provide a basis for recommending grazing cattle with sheep rather than cattle alone, but do provide some basis for recommending co-grazing of sheep and cattle using rotational rather than continuous stocking.

Many Neolithic settlements in southwest Asia maintained economic dependence on domestic caprine herds over long periods. This thesis explores the success of sheep herding in one 1200 year-old Neolithic settlement – Çatalhöyük, Central Anatolia (7400 – 6200 cal. BC). The evidence from two datasets is used to expand knowledge of the seasonal management of domestic sheep herds and their food resources. Successful herding is measured in terms of being able to maintain good husbandry practices whilst meeting the needs of the settlement. Samples of archaeological sheep’s teeth from Çatalhöyük are used in two ways: sequential oxygen isotope values from a sheep’s second mandibular molar give seasonality evidence during the first year of a sheep’s life, and are used to establish the birth season and mobility patterns over the year. Dental microwear analysis of the same tooth’s occlusal surface provides evidence of the dietary regime in the last few weeks of that sheep’s life, and is used to distinguish the type and quality of diet before slaughter. Together, the data outline a life history for each sheep, and are used to reveal the pattern of herding control and food resource manipulation. Çatalhöyük is within the habitat of wild sheep, where palaeoenvironmental modelling suggests that domestic herd management could have proceeded in the wider landscape with minimal niche construction. However settlement demands, both economic and social, might have prompted more convenient solutions, reliant on more extensive niche construction in a more limited local environment. The herders’ ability, or commitment, to maintaining best husbandry practices is explored by bringing the ethology of sheep to an interpretation of how environmental possibilities might have been utilized.

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This study aims to examine the introduction of the Dorper breed in Pernambuco state, from the point of view of the concepts of innovation, entrepreneurship and strategy, presented the motives, sources, evolution and the benefits of introduction of this innovation for the producers who decided to invest in the activity of the sheep industry from this race. For this we used a theoretical base for innovation with their definitions and classifications including that of incremental innovation, which is reports that research since the introduction of Dorper sheep in the state does not replace other race, but to improve what already existed. In the case of entrepreneurship was mentioned this topic lead to innovation and showed that this link is an interdependence where the entrepreneur is a major element of the innovation process. Still regarding the management of innovation was the theme set strategies, focusing on what these are decisions that guide the lines of action that lead to the achievement of goals and are used by innovators to differentiate themselves and be more competitive. The methodology incorporated items from the general objective of this work under a scheme that focused on three aspects of innovation, sources, evolution and results. This approach generated a questionnaire that guided the collection of primary data of this work to the producers of the elite flock of Dorper sheep in the state of Pernambuco. The results show that the production of Dorper ewes is feasible to those who decided to invest in this race over these 10 years of its existence in the state of Pernambuco, and this activity was capable of providing those producers tangible and intangible benefits.
Este trabalho tem por objetivo analisar a introdução da raça Dorper no estado de Pernambuco sob o ponto de vista dos conceitos de inovação, empreendedorismo e estratégia, apresentado as motivações, fontes, evolução e os benefícios resultantes da introdução desta inovação para os produtores que decidiram investir na atividade da ovinocultura a partir desta raça. Para isso foi utilizada uma base teórica sobre inovação com as suas definições e classificações entre elas a de inovação incremental, a qual se reporta essa pesquisa, visto que a introdução dos ovinos dorper no estado não veio para substituir outra raça e sim para melhorar as que já existiam. Tratando-se de empreendedorismo foi feita referência da ligação deste tema com a inovação e mostrou-se que esse elo tem uma interdependência, onde o empreendedor é um dos elementos principais do processo inovativo. Ainda referente à gestão da inovação foi colocado o tema estratégias, enfocando que estas são decisões que norteiam as linhas de ação que levam à obtenção dos objetivos e são utilizadas pelos inovadores para se diferenciarem e serem mais competitivos. A metodologia incorporou os itens do objetivo geral deste trabalho sob um esquema que enfocou três vertentes da inovação, as fontes, a evolução e os resultados. Este enfoque gerou um questionário que orientou a coleta dos dados primários deste trabalho junto aos produtores do rebanho ovino de elite da raça dorper no estado de Pernambuco. Os resultados mostram que a produção de ovinos da raça dorper é viável aos que decidiram investir nesta raça ao longo destes 10 anos de sua existência no estado de Pernambuco, sendo esta atividade capaz de proporcionar a esses produtores benefícios tangíveis e intangíveis.

The aim of this thesis was to investigate contrasting pasture management strategies on the foraging behaviour, pasture production, carcass characteristics, herbage intake, faecal gas emissions and methane emission by sheep grazing Italian ryegrass (Lolium multiflorum) pastures. The experiment was carried out in 2014 and 2015. The experimental design was a randomized complete block with four replicates and two grazing strategy treatments (traditional rotational stocking method – RT meaning pre- and post-grazing target heights of 25 and 5 cm, respectively and, “rotatinuous stocking” – RN with pre- and post-grazing target heights of 18 and 11 cm, respectively). The grazing management was based on a 1-day strip-grazing regime. Male castrated sheep were used. The actual average sward heights for the RN treatment were 17.9 and 11.1 cm (pre- and post-grazing, respectively) and 27.1 and 7.8 cm for the RT (pre- and post-grazing, respectively). The stocking period in 2014 was 146 and 140 days (RN and RT, respectively) and in 2015 it was 155 and 146 days (RN and RT, respectively). The diurnal animal activities (grazing, ruminating and resting time) did not differ between treatments, with average of 439.6, 166.9 and 85.0 minutes, respectively. The bite rate, feeding station per min and steps per min were greater at the RN than the RT treatment. Grazing time and bite rate were greater in the afternoon than morning in both treatments. Therefore, the daily herbage intake by sheep grazing Italian ryegrass was greater for the RN than the RT treatment (CHAPTER II). The herbage production in the RN was 28% higher than the RT treatment. Individual average daily gain and live weight gain per hectare were greater in the RN than the RT treatment (CHAPTER III). RN treatment presented greater final live weight, carcass and commercial cut weights from grazing sheep than RT treatment (CHAPTER IV). RN treatment had a faecal chemical quality greater than RT treatment, resulting in a greater daily nitrogen excretion per animal and greater faecal CH4 and N2O emissions (CHAPTER VI). The “rotatinuous stocking” (RN) was the better grazing management strategy for mitigation of CH4 emissions by sheep grazing Italian ryegrass, emitting 64% less CH4 per unit area and 170% less CH4 per unit of animal product than the traditional rotational stocking method (RT) (CHAPTER V).

Dissertação de Mestrado Integrado em Medicina Veterinária
Infections caused by gastrointestinal parasites have been described as one of the most important issues regarding small ruminant production. They induce major losses, causing a reduction in weight gain, poor feed utilization and consequently a decreased productivity. They can also be fatal, so their control measures mean a lot of investment. The main objectives of this study were to characterize the presence and level of parasitism of small ruminants in nine farms located in the region of Lisbon and Tagus Valley, as well as, the presence and level of anthelmintic resistance cases in five of the nine farms. The farms had different types of production and deworming systems, giving a generalized assessment of the current parasitological situation regarding small ruminants in that region. The anthelmintic efficacy study was performed in a dairy goats’ farm using eprinomectin (Eprinex® Pour-on), in two mixed (both sheep and goats) farms using fenbendazole (Panacur® 2,5%) and in two sheep flocks using an association of closantel and mebendazole (Seponver® Plus). The overall presence of gastrointestinal parasites in the nine farms was 89%. All farms were found to have positive animals to at least one type of gastrointestinal parasite, which pronounces a widespread infection with gastrointestinal parasites in the region. The most frequent encountered eggs were from strongyle type, followed by oocysts of Eimeria spp., eggs from Strongyloides papillosus and Moniezia expansa. Regarding the ranking of the parasitism level based on the eggs per gram (EPG) counts, five farms had more than 50% of the animals ranked in the low level of infection category (with less than 500 EPG), three farms had all three types of classifications with similar proportions (about 35%) and one farm had 75% of the animals ranked in the high level of infection category, with more than 1500 eggs per gram. Regarding the anthelmintic efficacy study, four out of five farms where the study was conducted presented anthelmintic resistance: two farms against fenbendazole and two farms concerning the association of closantel and mebendazole. The present study shows that even though there was a generalized infection by gastrointestinal parasites in the region, this infection appeared not to have fatal repercussions when at low levels. However, when anthelmintic efficacy was required it was not at the levels as it was supposed to be, according to the literature the first one to be reported in in the region of Lisbon and Tagus Valley, which announces an increase of anthelmintic resistant nematode strains in small ruminant production in our country.
ABSTRACT - As infeções provocadas por parasitas gastrointestinais têm sido descritas como um dos fatores mais importantes relacionados com a produção de pequenos ruminantes. Estas provocam graves prejuízos, reduzindo o ganho médio diário e a utilização dos alimentos, levando uma menor produtividade. Estas infeções podem também tornar-se fatais, pelo que as suas medidas de controlo exigem grandes investimentos. Uma das condutas mais comuns para ultrapassar esta situação prende-se com o uso frequente e desnecessário dos anti-helmínticos, sem avaliar a real necessidade da sua aplicação. Todavia, uma vez que esta atividade leva ao aparecimento e aumento das resistências por parte dos parasitas, esta prática requer uma avaliação e consequente alteração. Por forma a adequar a abordagem ao seu controlo, torna-se imperativo o conhecimento dos parasitas gastrointestinais mais comuns na produção dos pequenos ruminantes. Estes consistem em protozoários do Filo Apicomplexa, helmintes da Classe Trematoda, da Classe Cestoda e do Filo Nematoda. No Filo Apicomplexa temos Eimeria spp., um género de coccídia transmitido através da contaminação fecal de comida e água. Trata se de um parasita intracelular, que destrói as células do seu hospedeiro e que provoca doença sobretudo em animais jovens ou debilitados. Cryptosporidium sp., também pertencente ao Filo Apicomplexa, trata-se de um parasita que infeta as células epiteliais do trato gastrointestinal de mamíferos, aves, répteis e peixes. Algumas espécies podem ser zoonóticas, o que aumenta a sua importância quando se lida com animais potencialmente infetados ou com águas potencialmente contaminadas. A Classe Trematoda compreende duas subclasses principais: Monogena e Digenea. Na subclasse Digenea, encontramos parasitas com um estilo de vida heteroxeno, ou seja, que requerem um hospedeiro intermediário (moluscos) e que apenas parasitam vertebrados. É o caso da Fasciola hepatica, de distribuição cosmopolita e que pode ser encontrado no fígado e ductos biliares de mamíferos herbívoros e de humanos. Os seus ovos são eliminados com a bílis para o lúmen intestinal e para o exterior através das fezes. Dicrocoelium dendriticum também se trata de um trematode encontrado nos ductos biliares de ruminantes, camelídeos, coelhos e outros mamíferos. Na Classe Cestoda encontramos parasitas achatados e segmentados, cujas formas adultas são hermafroditas. Nesta Classe inclui-se o género Moniezia, de distribuição cosmopolita e cujo ciclo de vida se inicia com a ingestão pelo hospedeiro intermediário de fezes contaminadas com ovos de Moniezia spp. Por fim, no Filo Nematoda, encontramos predominantemente parasitas de corpo cilíndrico e com um ciclo de vida direto. Neste Filo inserem-se os géneros Haemonchus, Teladorsagia, Trichostrongylus, Cooperia, Nematodirus, Chabertia, Oesophagostomum, Bunostomum, Trichuris e Strongyloides. Atualmente existem três principais grupos de anti-helmínticos utilizados no tratamento das helmintoses nos pequenos ruminantes: os benzimidazóis, como o febendazol, albendazol e mebendazol; as lactonas macrocíclicas como a ivermectina, eprinomectina e moxidectina e os Imidazotiazóis como o levamisol. Existe ainda o grupo das Salicinalinidas e fenóis substitutos onde se insere o closantel. Não obstante, o seu uso indiscriminado tem levado ao desenvolvimento de resistências aos anti-helmínticos, que tem vindo a ser reportado a nível mundial, sobretudo no grupo dos benzimidazóis e das lactonas macrocíclicas; estas estirpes resistentes de nematodes gastrointestinais têm sido encontradas nos Estados Unidos da América, no Brasil, em África, na Austrália, Nova Zelândia e Europa. Para o aparecimento das resistências contribui o facto de que, embora sejam vistos e tratados como semelhantes, os ovinos e os caprinos diferem entre si de diversas formas, sendo que os caprinos possuem uma taxa metabólica superior e requerem, portanto, doses superiores no que diz respeito à administração de fármacos. A maioria dos anti helmínticos não se encontram licenciados para esta espécie e as doses apropriadas para a mesma são raramente conhecidas. Os caprinos geralmente requerem doses 1.5 a 2 vezes superior à dos ovinos, contudo, uma vez que são tratados conjuntamente e de acordo com a dose recomendada para estes últimos, acabam por receber uma dose inferior à necessária, promovendo o aparecimento da resistência anti-helmíntica. O aparecimento de estirpes de nematodes resistentes aos anti-helmínticos tem sido frequentemente reportado em pequenos ruminantes, o que levou à necessidade de criar novas abordagens no controlo e tratamento das parasitoses. Um ponto fundamental para o combate à resistência anti-helmíntica trata-se da manutenção da população em refúgio, constituída pelos parasitas presentes em animais não tratados, pelas suas fases de vida livre (por exemplo, na pastagem) e pelos seus estádios não afetados pelo tratamento. Sugere-se então que um produtor, aquando da passagem dos animais para o pasto, deverá deixar os animais mais saudáveis por tratar, para que os parasitas suscetíveis possam sobreviver e reproduzir-se com parasitas resistentes, propagando assim os genes suscetíveis e atrasando o desenvolvimento da resistência aos anti helmínticos. Além da manutenção da população em refúgio, outras medidas deverão ser implementadas, tais como: a aplicação do método FAMACHA©, suplementação com proteína por forma a aumentar a resistência e resiliência ao parasitismo, a introdução de fungos nematófagos na alimentação, formulação de vacinas, o uso de plantas com propriedades anti-helmínticas e a seleção de animais resistentes ao parasitismo. A situação de resistência aos anti-helmínticos na produção de pequenos ruminantes em Portugal é desconhecida, pelo que os principais objetivos deste estudo foram caracterizar a presença e o nível de parasitismo de pequenos ruminantes em nove explorações localizadas na região de Lisboa e Vale do Tejo, assim como avaliar a presença e o nível de resistência anti-helmíntica em cinco das nove explorações. As explorações selecionadas possuíam diferentes sistemas de produção e desparasitação, por forma a demonstrar de uma forma generalizada o estatuto parasitário dos pequenos ruminantes na região. Uma exploração encontrava-se localizada no distrito de Lisboa, uma no distrito de Setúbal e sete no distrito de Santarém. Quatro das explorações encontravam-se em regime intensivo e cinco em regime extensivo, sendo que das primeiras, duas eram constituídas apenas por caprinos, uma por ovinos e uma por ambas as espécies, ou seja, mista. As explorações extensivas eram constituídas por três rebanhos de ovinos e dois rebanhos mistos. As idades dos animais estavam compreendidas entre os seis meses e os nove anos e as colheitas foram efetuadas entre Setembro de 2018 e Janeiro de 2020. As fezes foram colhidas diretamente da ampola retal dos animais e identificadas e analisadas individualmente, por forma a averiguar o nível de parasitismo através da contagem de ovos por grama pela técnica de McMaster. Foram também realizadas coproculturas para averiguar os géneros de estrôngilos gastrointestinais predominantes. O estudo da eficácia anti-helmíntica foi realizado numa exploração de cabras leiteiras recorrendo à eprinomectina (Eprinex® Pour-on), em duas explorações mistas recorrendo ao uso de febendazol (Panacur® 2,5%) e em duas explorações de ovinos usando uma associação de closantel e mebendazol (Seponver® Plus). A presença geral de parasitas gastrointestinais nas nove explorações foi de 89.27%, com uma diferença significativa entre ovinos e caprinos (76.85% e 92.78%, respetivamente). Todas as explorações demonstraram ter animais positivos a pelo menos um tipo de parasita gastrointestinal, o que revela uma infeção generalizada por parasitas gastrointestinais na região. Os ovos detetados com maior frequência foram os do tipo estrongilídeo (88.88%), seguido de oocistos de Eimeria spp. (66.66%), ovos de Strongyloides papillosus (55.55%) e de Moniezia expansa (11.11%). A média da contagem de ovos por grama (OPG) nos ovinos foi de 2029, com contagens com valores entre 0 e 21300. Nos caprinos, a média de OPG foi de 606 com contagens com valores entre 0 e 5850. Em relação à contagem dos oocistos por grama (OOPG), foram encontradas médias de 47 OOPG, com valores entre 0 e 2500, e 109 OOPG, com valores entre 0 e 850, respetivamente. Na classificação do nível de parasitismo baseado na contagem de OPG, cinco explorações tiveram mais de 50% dos seus animais classificados no nível baixo de infeção (menos de 500 OPG), três explorações tiveram os três tipos de classificação em proporções idênticas e uma exploração teve 75% dos seus animais classificados no nível alto de infeção, com mais de 1500 OPG. Por fim, no estudo da eficácia dos anti-helmínticos, quatro das cinco explorações apresentaram resistência: duas ao febendazol e duas à associação de closantel e mebendazol. O presente estudo demonstrou que embora se tenha observado uma infeção generalizada por parasitas gastrointestinais na região, esta infeção não revelou ter repercussões fatais quando se encontrava em níveis baixos. Contudo, quando foi necessária a eficácia dos anti-helmínticos, esta não se encontrou aos níveis esperados, e segundo a literatura, a primeira a ser reportada na região de Lisboa e Vale do Tejo, o que sugere um aumento de estirpes de nematodes resistentes aos desparasitantes no nosso País.
N/A

Um dos principais desafios do setor da ovinocultura no Brasil é verificar sua competitividade em termos de custos e preços, e possuir recursos e ferramentas que permitam indicar quais condições poderiam ser satisfeitas para sua viabilização. A presente pesquisa teve como finalidade desenvolver um modelo para cálculo e análise de custo da ovinocultura e, a partir dele, elaborar um índice de custo de produção (ICPC) para acompanhar sua evolução. Painéis foram realizados em regiões relevantes do estado de São Paulo para definir as características de propriedades representativas de criação de cordeiros, e estas foram tomadas como base para a construção do modelo. As mesorregiões selecionadas foram as de São José do Rio Preto, Bauru, Araçatuba, Campinas e Piracicaba. Em seguida, foi definido o modelo de cálculo de custo de produção, com base na Teoria Econômica. Foram então acompanhados os preços dos insumos e calculados mensalmente os custos de produção para as propriedades representativas, permitindo a elaboração dos índices de custo. Realizou-se então a análise das elasticidades dos preços dos insumos e dos coeficientes zootécnicos. Por fim, foi conduzida a validação do ICPC junto a produtores e técnicos. Ficou nítido que a atividade enfrenta muitos desafios, em sua maioria técnicos, que necessitam ser trabalhados para permitir a viabilidade econômica da criação de cordeiros. A aplicação da Teoria Econômica ao cálculo dos custos de produção é imprescindível para o desenvolvimento de modelos de cálculo de custos. O modelo desenvolvido possui potencial de gerar informações importantes para a tomada de decisões na propriedade, como foi exemplificado através dos estudos das composições dos custos e das elasticidades. O ICPC foi validado e tem potencial para colaborar com a organização do setor.
One of the main challenges for the sheep industry in Brazil is to verify its competitiveness in terms of costs and prices, and to have resources and tools that allow indicating which conditions should be satisfied for its viability. This research had the aim of developing a model for calculation and analysis of production costs of lamb and, from that, elaborating a production cost index (ICPC) to follow its evolution over time. The regions assessed were São José do Rio Preto, Bauru, Araçatuba, Campinas and Piracicaba. Panel meetings were performed in these regions to define representative farms of sheep raising, which were taken as basis for the construction of the cost calculation model. Afterwards, the elasticities of input prices and technical coefficients were analyzed. Finally, the validation of the ICPC was conducted with the participation of sheep producers and professionals. It was clear that the activity faces many challenges, mostly technical, that need to be solved to allow economic feasibility of sheep raising. The application of Economic Theory to the calculation of production costs is essential for the development of cost calculation models. The developed model has potential to generate important information, that can help producers on decision making, as exemplified by the analyzes of cost compositions and elasticities. ICPC was approved and can collaborate with the organization of the sheep industry.

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The objective of this work was to determine the epidemiological situation of Bluetongue virus (VLA) infection in sheep herds and to characterize the technological and sanitary aspects in the states of Alagoas (AL), Ceara (CE), Maranhao (MA) , Paraiba (PB), Piaui (PI), Rio Grande do Norte (RN) and Sergipe (SE). For this purpose, 226 farms visited and applied a questionnaire where blood of 2.692 apparently healthy sheep collected. In the present study, a mean prevalence in the northeast of 60,62% (137/226) of positive animal properties and 26,52% (714/2.692) of seropositive sheep. A mean VLA seroprevalence of 33,06% (162/490) in sheep and 82,93% (34/41) in the herds, with at least one positive animal observed in the state of CE. In AL, a seroprevalence of 2,55% was observed (7/275) from the animals and 21.74% (5/23) on farms. In the MA State, 64,13% (177/276) of the animals and 100% (23/23) of the herds were positive. Regarding the RN State, of the 33 properties surveyed, 12 (36,36%) had seroreagents and 16 of the animals studied (4,04%) were positive. In PB State, 2,82% (8/284) of the sheep were seroreagent and of the 24 farms analyzed, 2 (8,33%) presented a positive animal. In the PI, 76,98% (291/378) of the animals and all the properties (32/32) were seroreagent. In SE State, 894% (53/593) of the sheep were positive and 58,0% (29/50) in the sampled herds showed positivity. There was a significant association (p <0,05) regarding the sex, age and degree of kinship of the animals. The acquisition of animals for replacement of the herds (p <0,05) (odds ratio = 5,87, 95% CI = 2,06-16,76, p = 0,001) was identified as a risk factor for BTV in the evaluated states. In this study, the technological and sanitary aspects verified that the breeding system most adopted in the Northeast was the extensive (84,07%), with the activity directed mainly to meat (84,07%). It was verified that the animals were handled in sheepfolds on 68,14% of the properties. The predominance of joint rearing with goats and cattle was too observed. It was verified that 81,42% of the properties had some kind of technical assistance and that only 31,86% of the owners invest in their professional qualification of the employees. The most adopted practices on farms were cleaning the facilities (67,70%) and disposal of animals (80,09%). It was observed that 60,18% of the farms apply some type of vaccine. It was also observed that worm was the biggest problem faced in sheep farms (97,80%), and 96,02% of the producers used vermifugation as the control method. Other health problems frequently reported by the interviewees were Myiasis (93,83%), Caseous Lymphadenitis (89,87%), Pododermatitis (87,67%) and Bronchopneumonia (81,94%). The results obtained in this work indicate that the BTV is present in the sheep herds of the states analyzed and that the exploitation of these in the Northeast has low technological level. It was also verified that the control of the diseases of these states is deficient, which explains, in part, the low productivity of the herds
O escopo deste trabalho foi determinar a situação epidemiológica da infecção pelo vírus da Língua Azul (VLA) e caracterizar os aspectos tecnológicos e sanitários nos rebanhos ovinos dos estados de Alagoas (AL), Ceará (CE), Maranhão (MA), Paraíba (PB), Piauí (PI), Rio Grande do Norte (RN) e Sergipe (SE). Para tanto, foram visitadas e aplicados questionários em 226 propriedades, onde coletou-se o soro de 2.692 ovinos, aparentemente saudáveis. Observou-se uma prevalência média no nordeste de 60,62% (137/226) de propriedades com animais positivos e 26,52% (714/2692) de ovinos soropositivos. No CE houve uma soroprevalência média do VLA de 33,06% (162/490) nos ovinos, e de 82,93% (34/41) nas propriedades com pelo menos um animal positivo. Em AL, foi verificada uma soroprevalência de 2,55% (7/275) nos animais, e de 21,74% (5/23) nos criatórios. Já no MA, 64,13% (177/276) dos animais e 100% (23/23) dos rebanhos foram positivos. Em relação ao RN, das 33 propriedades pesquisadas, 12 (36,36%) tiveram sororreagentes e dos 396 animais estudados, 16 (4,04%) foram positivos. Na PB, 2,82% (8/284) dos ovinos foram sororreagentes e dos 24 rebanhos analisados, 2 (8,33%) apresentaram animal positivo. No PI, 76,98% (291/378) dos animais e todas as propriedades (32/32) foram sororeagentes. Em SE, 8,94% (53/593) dos ovinos foram positivos e nos rebanhos amostrados, 58% (29/50) apresentaram positividade. Houve associação significativa (p<0,05) quanto ao sexo, idade e grau de sangue dos animais. A aquisição (compra) de animais para reposição do plantel (p<0,05) (odds ratio = 5,87; IC 95% = 2,06-16,76; p=0,001) foi identificada como fator de risco para Língua Azul nos estados avaliados. No estudo dos aspectos tecnológicos e sanitários verificou-se que o sistema de criação mais adotado no Nordeste foi o extensivo (84,07%), com a atividade voltada majoritariamente para corte (84,07%), sendo verificado que os animais eram manejados em apriscos em 68,14% das propriedades. Foi observada a predominância de criação conjunta com caprinos e com bovinos. Verificou-se que 81,42% das propriedades possuíam algum tipo de assistência técnica e que apenas 31,86% dos proprietários investiam na qualificação profissional de seus funcionários. As práticas mais adotadas nas fazendas foram a limpeza das instalações (67,70%) e o descarte de animais (80,09%). Quanto à vacinação dos rebanhos, foi observado que 60,18% dos criatórios aplica algum tipo de vacina. Observou-se, também, que a verminose foi o maior problema enfrentado nos criatórios de ovinos (97,80%), sendo que 96,02% dos produtores utilizam como método de controle a vermifugação. Outros problemas sanitários frequentemente relatados pelos entrevistados foram a Miíase (93,83%), Linfadenite Caseosa (89,87%), Pododermatite (87,67%) e Broncopneumonia (81,94%). Os resultados obtidos neste trabalho indicam que o VLA encontra-se presente nos ovinos dos estados analisados e que a exploração destes no Nordeste possui baixo nível tecnológico. Verificou-se, também, que o controle das enfermidades destes estados é deficiente, o que explica, em parte, a baixa produtividade dos rebanhos
2018-03-19

As ações conjuntas vêm sendo adotadas por vários segmentos produtivos visando desempenho e competitividade dos empreendimentos para garantir a presença em mercados mundiais. O agronegócio tem importância no processo de desenvolvimento econômico do Brasil como um todo e do Estado do Rio Grande do Sul pela sua capacidade de geração de riquezas, criação de empregos, transferência e circulação de renda, desenvolvimento de novas tecnologias, pesquisas e desenvolvimento da ciência em geral. Estudos também avaliam o potencial das parcerias rurais, enfocando cinco capitais como categorias de ativos que interferem na formação de parcerias, pois é de grande importância a compreensão dos produtores rurais sobre a estreita relação entre a expansão dos bens de capital e a capacitação organizacional. O problema verificado na presente pesquisa refere-se ao processo de formação de estratégias conjuntas no processo de criação de ovinos em escala local, originando a questão-problema que conduziu a pesquisa: Quais os principais fatores de produção (capitais) que contribuem e que limitam o processo de formação de estratégias conjuntas visando à ampliação da capacidade de produção e a competitividade? O estudo teve por objetivo analisar estes fatores. Para isso, foi utilizado o método de investigação de natureza qualitativa e descritiva, a fim de apreender as características do fenômeno e projetar possíveis melhorias no processo proporcionando uma nova visão do problema. A investigação teve início a partir da literatura originária dos diversos autores com estudos relacionados à formação de estratégias conjuntas. Foram definidas categorias de análise baseadas na avaliação de fatores de produção, denominados de capitais humano, financeiro, natural, social e físico. A região selecionada para o desenvolvimento do estudo abrange as cidades de Santa Maria, São Pedro do Sul, Dilermando de Aguiar e São Martinho da Serra, no Estado do Rio Grande do Sul, com uma população-alvo constituída de produtores de pequeno porte na produção de ovinos de lã e de corte. Foram aplicadas entrevistas semi-estruturadas como instrumento de coleta de dados. Os resultados encontrados evidenciaram que os produtores apresentam potencial capacidade de desenvolver estratégias conjuntas, com estrutura suficiente para obter eficiência, sendo os fatores de convivência, os quais estão relacionados ao capital social, considerados como os indutores do processo. O estudo evidenciou ainda falta de entendimento e compreensão dos pesquisados com as questões relativas às preocupações ambientais.
Joint actions are being taken by many productive segments targeting performance and competitiveness of projects to ensure its presence in world markets. Agribusiness has importance economic development process in Brazil\'s as a whole and the State of Rio Grande do Sul for its ability to generate wealth, create jobs, transference and circulation of income, development of new technologies, research and development of science in general. Studies also evaluate the potential of rural partners, focusing on five capitals as asset categories that interfere in the formation of partners, it is very important to understand the rural farmers about the close relationship between the expansion of capital assets and organizational skills. The problem encountered in this study refers to the formation of joint strategies in the process of sheep farming on a local scale causing the problem-question who led the research : What are the main factors of production (capital) which contribute and which limit the process of formation of joint strategies aimed at expanding of production capacity and competitiveness? The study aimed to analyze these factors. For this, we used the method of investigation of qualitative and descriptive in nature, a view to apprehend the characteristics of the phenomenon and projecting possible improvements in the process by providing a new view of the problem. The investigation began from the literature of the different authors with studies associated to the formation of joint strategies . were defined categories of analysis based on the evaluation of factors of production, called human capital, financial, natural, social and physical . The region selected for the development of the study includes the cities of Santa Maria, São Pedro do Sul, Dilermando de Aguiar and São Martinho da Serra in the state of Rio Grande do Sul, with a target population consists of small producers in the production of sheep wool and cutting. Semi-structured interviews were applied as a tool for data collection. The findings results indicated that producers have the potential capacity to develop joint strategies, with structure large enough to achieve efficiency, and the cohabitation factors, which are related to the social capital, considered as inducers of process. The study also revealed a lack of understanding and comprehension of respondents with issues related to environmental concerns.

The Utah prairie dog (Cynomys parvidens) was listed by the U.S. Fish and Wildlife Service as an endangered species in 1973 because of range-wide population declines. The species was reclassified as threatened in 1984 because of population increases on private lands. Habitat fragmentation coupled with a lack of suitable habitat has impeded species recovery. Desired species habitat conditions include 0-8% shrub cover, 12-40% cool-season grass cover, and 1-10% perennial forb cover. Cool-season grasses are critical for Utah prairie dogs because of high spring energy requirements. Past research suggested that reducing shrub cover may increase cover of desired grasses and forbs. From 2008-2010, I evaluated the effects of high intensity fall sheep grazing and low application of herbicide (tebuthiuron) as tools to reduce shrub cover and enhance grass and forb cover on the Awapa Plateau Utah prairie dog recovery area in south-central Utah. I placed 1700 ewes in 4 ha stratified and randomly selected plots until >70% vegetation utilization was achieved. Five additional randomly-selected plots were treated with tebuthiuron at a rate of ~1.68 kg/ha. Percent cover of grass, forbs, and shrubs was recorded on treatments and paired control plots in June 2009 and 2010 to determine treatment vegetation responses. I also affixed 22 juvenile Utah prairie dogs with radio transmitters to determine if over-winter survival differed relative to treatment. Live shrub cover was lower on grazed plots in year 1 (P<0.001) and in year 2 (P=0.015). Dead shrub cover in grazed plots was higher in year 1 (P<0.001). Grazed plots exhibited increased forb cover from year 1 (P=0.104) to year 2 (P=0.008). Live shrub cover was lower in herbicide plots in year 2 (P=0.002). Dead shrub cover in herbicide plots was higher in year 2 (P=0.006). Tebuthiuron and grazed plots exhibited a reduction in shrub height (P=0.010, P=0.026, respectively). Tebuthiron plots exhibited less grass cover (P=0.034). Intensive sheep grazing and a low application of tebuthiuron reduced both shrub cover and vertical structure, but failed to increase the percent of grass cover when compared to the control plots. All plots exhibited reduced grass cover in 2010 in response to below normal precipitation. However, percent grass cover was higher on the grazed plots. It is possible that low inherent site productivity in combination with below normal average precipitation compromised treatment effects. Because of radio transmitter failure, I was not able to obtain survival data after hibernation. Prairie dog counts and weights did not differ by treatment type. If climate change reduces overall precipitation on the Awapa Plateau, recovery of the Utah prairie dog on this site will be problematic.

This study consisted of two sheep grazed dryland pasture experiments. Experiment l compared sheep production from 3-year-old cocksfoot based pastures grown in combination with white, Caucasian, subterranean or balansa clover with a ryegrass-white clover pasture and a pure lucerne forage. Sheep liveweight gain per head from each pasture treatment and the pure lucerne stand was recorded in the 2006/07 and 2007/08 seasons. The cocksfoot-subterranean clover pasture provided equal (381 kg LW/ha in 2006) or higher (476 kg LW/ha in 2007) animal production in spring and gave the highest total animal production (646 kg LW/ha) averaged across years of the five grass based pastures. However, total annual liveweight production from lucerne was higher than any grass based pasture mainly due to superior animal production during summer when lucerne provided 42-85% higher animal production than any of the grass based pastures. In Experiment 2, the effect of stocking rate (8.3 (low) and 13.9 (high) ewes + twin lambs/ha) and time of closing in spring on lamb liveweight gain, pasture production and subterranean clover seedling populations was monitored over 2 years for a dryland cocksfoot-subterranean clover and ryegrass-subterranean clover pasture in Canterbury. In both years, twin lambs grew faster (g/head/d) in spring at low (327; 385) than high (253; 285) stocking rate but total liveweight gain/ha (kg/ha/d) was greater at high (7.26; 7.91) than low (5.43; 6.38) stocking rate. Ewes also gained 0.5 and 1.5 kg/head at the low stocking rate in 2006 and 2007 respectively but lost 0.2 kg/head in 2006 and gained 0.3 kg/head at high stocking rate in 2007. Mean subterranean clover seedling populations (per m²) measured in autumn after grazing treatments in the first spring were similar at both low (2850) and high (2500) stocking rate but declined with later closing dates in spring (3850, 2950, 2100 and 1700 at 2, 4, 6, 8 weeks after first visible flower). Seedling populations measured in autumn after grazing treatments in the second spring were also unaffected by stocking rate (low 1290, high 1190) but declined with later closing dates in spring (1470, 1320 and 940 at 3, 5 and 8 weeks after first flowering, respectively). The effect of stocking rate and closing dates in spring on pasture and clover production in the following autumn was similar to the effects on seedling numbers in both years. However, clover production in the following spring was unaffected by stocking rate or closing date in the previous year at the relatively high seedling populations generated by the treatments. This was presumably due to runner growth compensating for lower plant populations in pastures that were closed later in spring. Subterranean clover runner growth in spring may not compensate in a similar manner if seedling numbers in autumn fall below 500/m². Mean annual dry matter production from cocksfoot and ryegrass pastures grown with and without annual clovers pasture production ranged from 6.4 to 12.4 t DM/ha/y but stocking rate (8.3 vs. 13.9 ewes/ha) during spring did not affect annual pasture production. Pastures overdrilled with annual clovers yielded 23-45% more dry matter production than pastures grown without annual clovers. The study confirms the important role of subterranean clover in improving pasture production and liveweight gains of sheep in dryland cocksfoot and ryegrass pastures. Lowering stocking rate from 13.9 to 8.3 ewes/ha was a less effective method of increasing seed production of subterranean clover in dryland pastures although it did lead to increased liveweight gain per head.

Increasing energy use has caused many environmental problems including global warming. Energy use is growing rapidly in developing countries and surprisingly a remarkable portion of it is associated with consumed energy to keep the temperature comfortable inside the buildings. Therefore, identifying renewable technologies for cooling and heating is essential. This study introduced applications of steel sheets integrated into the buildings to save energy based on existing technologies. In addition, the proposed application was found to have a considerable chance of market success. Also, satisfying energy needs for space heating and cooling in a single room by using one of the selected applications in different Köppen climate classes was investigated to estimate which climates have a proper potential for benefiting from the application. This study included three independent parts and the results related to each part have been used in the next part. The first part recognizes six different technologies through literature review including Cool Roof, Solar Chimney, Steel Cladding of Building, Night Radiative Cooling, Elastomer Metal Absorber, and Solar Distillation. The second part evaluated the application of different technologies by gathering the experts’ ideas via performing a Delphi method. The results showed that the Solar Chimney has a proper chance for the market. The third part simulated both a solar chimney and a solar chimney with evaporation which were connected to a single well insulated room with a considerable thermal mass. The combination was simulated as a system to estimate the possibility of satisfying cooling needs and heating needs in different climate classes. A Trombe-wall was selected as a sample design for the Solar Chimney and was simulated in different climates. The results implied that the solar chimney had the capability of reducing the cooling needs more than 25% in all of the studied locations and 100% in some locations with dry or temperate climate such as Mashhad, Madrid, and Istanbul. It was also observed that the heating needs were satisfied more than 50% in all of the studied locations, even for the continental climate such as Stockholm and 100% in most locations with a dry climate. Therefore, the Solar Chimney reduces energy use, saves environment resources, and it is a cost effective application. Furthermore, it saves the equipment costs in many locations. All the results mentioned above make the solar chimney a very practical and attractive tool for a wide range of climates.

Realizar a análise econômica de uma produção agropecuária não é algo trivial, seja pela enorme heterogeneidade entre cada unidade produtiva, seja porque utiliza muitos recursos naturais, alguns de difícil mensuração. Há diversos métodos disponíveis para o cálculo do custo de produção, que é o indicador chave para a análise da viabilidade de um empreendimento. O desafio é permitir que a projeção da atividade no horizonte produtivo seja a mais real e dinâmica possível. A simulação computacional é atualmente uma das mais poderosas ferramentas de análise disponível para o planejamento, projeto e controle de sistemas complexos, e vem sendo cada vez mais utilizada e difundida. Simular compreende a elaboração de um método de experimentação que, através da construção de modelos de um sistema real, procura descrever comportamentos, construir teorias ou hipóteses por meio do observado e predizer comportamentos futuros. O uso de modelos de simulação, que incorporem o risco e a probabilidade dentro produção animal, pode ser uma alternativa tanto técnica - auxiliando na tomada de decisão, gestão e planejamento pecuário, quanto científica - permitindo a avaliação de efeitos de resultados da pesquisa e identificação de limitantes que podem incentivar o desenvolvimento de pesquisas futuras. O modelo de simulação híbrido - baseado em simulação de eventos discretos e baseado em agentes, aqui proposto - visou identificar coeficientes zootécnicos e os critérios de manejo que mais impactam a produção de ovinos de corte. Esse modelo de simulação computacional híbrido possui caráter dinâmico e probabilístico, com eventos marcados no tempo (estação de monta, gestação, parição, desmame, engorda, abate, entre outras) e complexos o suficiente para que seus agentes sofram alterações tanto no tempo quanto em resposta a ocorrência ou não das variáveis ligadas a eles. Os resultados dos experimentos e dos cenários estudados revelaram que dentre os índices zootécnicos das matrizes, a ocorrência de aborto gera maior impacto na taxa de abate e financeiramente na margem líquida operacional. Contudo, analisando as variáveis tanto para matrizes como para cordeiros, a mortalidade neonatal, até os cinco dias de vida dos cordeiros, demonstrou ser o ponto fundamental para a lucratividade da atividade. A estabilização do rebanho foi mais afetada pela presença de matrizes adultas no plantel, que culminaram no aumento no número de cordeiros por matriz. Os resultados da análise dos fluxos de caixa de 30 anos, a uma taxa mínima de atratividade de 6,17% aa, permitiram constatar que iniciar a atividade com número muito reduzido de matrizes é o cenário menos interessantes, com taxa interna de retorno negativa para o período de análise. O estudo do fluxo de caixa permitiu atribuir a 200 matrizes como o tamanho de rebanho inicial mais interessante (TIR = 3,30% aa). Assim, o uso de simuladores híbridos baseados em simulação de eventos discretos e baseados em agentes, para estudos na pecuária nacional, apresentou-se como ferramenta com grande potencial de contribuição, no sentido de permitir conhecer os resultados possíveis das diferentes combinações tecnológicas disponíveis. O modelo ainda permite ser utilizado como ferramenta de estudo e análise para a cadeia produtiva, contribuindo na orientação aos cientistas, auxiliando no direcionamento de seus esforços no desenvolvimento de futuras pesquisas
Conduct an economic analysis of agricultural production is not trivial, either by its enormous heterogeneity between each production unit, or because it uses many natural resources, some of which are difficult to measure. There are several methods available for calculating the cost of production, which is the key indicator for assessing the feasibility of a project. The challenge is to allow the projection of activity in the productive horizon in the most real and dynamic form as possible. The computer simulation is currently one of the most powerful analysis tools available for planning, design and control of complex systems and is being increasingly used and disseminated. Simulate includes the development of a method of testing by building models of a real system, that seeks to describe behaviors, build theories or hypotheses through noted and predicted future behaviors. The use of simulation models that incorporate uncertainty and probability in animal production can be both an alternative technique - assisting in decision-making, management and livestock planning; as scientific - allowing the evaluation of the research results of effects and identification of limiting that may encourage the development of future research. The model of hybrid simulation - based on discrete event simulation and on agent-based, proposed here - aimed to identify factors husbandry and management criteria that most affect the production of meat sheep. The model of hybrid computer simulation have dynamic and probabilistic characteristics, with events scheduled in time (breeding season, pregnancy, parturition, weaning, fattening, slaughter, etc.) and enough complexity that its agents be adversely affected both in time and in response to the occurrence or not of variables linked to them. The results of the experiments and the scenarios studied showed that among the zootechnical indexes of the sheep, the occurrence of abortion generates a greater impact on the slaughter rate and financially in the net operating margin. However, analyzing the variables for both sheep and lambs, neonatal mortality, up to the lambs\' five days of life, proved to be the fundamental point for the profitability of the activity. The stabilization of the herd was more affected by the presence of adult sheep in the herd, which culminated increasing the number of lambs per sheep. The results of the analysis of the 30-year cash flows, at a minimum attractiveness rate of 6.17% per year, showed that starting the activity with a very small number of sheep was the least interesting scenario, with a negative internal rate of return for the analysis period. The study of the cash flow allowed to assign to 200 sheep as the most interesting initial herd size (IRR = 3.30% per year). Thus, the use of hybrid simulators, based on discrete event simulation and agent-based for studies in national livestock, is presented as a tool with great potential to contribute, to allow knowing the possible outcomes of different combinations of available technology. The model also allows to be used as a study tool and assessment of different technological combinations for the production chain, contributing to the guidance of scientists, assisting their efforts in the development of future research

Ce travail de thèse explore les aspects organisationnels de l’accompagnement local de la transition agroécologique. Cet accompagnement nécessite d’articuler différents processus individuels et collectifs de transformation des activités de la production et du développement agricole. En construisant un dispositif de recherche-action au sein d’un projet de transition agroécologique porté par une association d’éleveurs et conseillers dans le rayon de Roquefort, nous mettons en oeuvre avec eux une forme d’expérimentation sociale qui nous permet de comprendre le problème de l’accompagnement de la transition à la fois sur le plan théorique et pratique. Dans notre cas, l’articulation des transformations individuelles et collectives a été permise par un travail de co-conception entre éleveurs et conseillers des outils de l’accompagnement des changements dans les fermes. Ce processus a permis de débattre de la diversité des modèles agricoles et des représentations des acteurs de la transition agroécologique au sein du groupe, ainsi que d’engager conjointement éleveurs et conseillers dans la transformation de leurs pratiques. Ces transformations ont été d'autant plus facilitées que la coconception a été envisagée comme un processus dialogique entre conception et expérimentation dans différentes situations réelles d’usage dans les fermes. A l’issue de ce travail, nous proposons une approche pragmatiste pour accompagner localement la transition agroécologique
We explore in this research the organizational dimensions of agroecological transition and the ways to support it locally. The support of agroecological transition requires connecting differentprocesses of individual and collective transformations of agricultural development and production activities. We design a device for action reseach within an agroecological transition project, carriedby a farmers and advisers association in the Roquefort area. We implement with them a social experiment to explore this problem both from theoretical and practical point of view. In our casethe connection between individual and collective transformation of participant activities required farmers and advisers to design together tools to accompany the agroecological transition on farms. This process allowed the debate about the diversity of agricultural models and representations that actors have regarding agroecological transition. It as well allows engaging advisers and farmers jointly in the agroecological transition. These transformations have been enhanced by the fact that the co-design process was organized as a dialogical process between design and experimentation of the tools in diverse real situations of use on farms. At the end of this journey, we propose to develop a pragmatist approach to accompany locally the agroecological transition

In the early 2000s, the Securities and Exchange Commission (SEC) called on firms to provide new MD &A disclosures about their critical accounting estimates. The new disclosures outline how reasonably likely changes in firms' highly uncertain accounting estimates would affect earnings. Because the new disclosure practice potentially highlights accrual estimates with a reduced level of reliability (i.e. greater estimation error) arising from uncertainty in the accrual measurement process, I examine whether the presence of a critical accounting estimate (CAE) disclosure partially explains cross-sectional variation in the value relevance of balance sheet items. Using a sample of non-financial and non-utility S &P 500 firms from 2004 to 2009, I find the value relevance of a balance sheet item is negatively associated with the presence of a related CAE disclosure. To corroborate my value relevance findings, I also examine whether the predictive value of accruals with respect to future cash flows and accrual noise, which are two accounting-based characteristics of useful accounting information, are associated with the presence of a CAE disclosure. I find the incremental predictive value of accruals with respect to future cash flows (accrual noise) is negatively (positively) associated with the presence of a CAE disclosure. Overall, these results suggest investors perceive balance sheet items accompanied by a related, account-specific CAE disclosure to have lower reliability, and consistent with investors' perceptions, accrual estimates have less predictive value and are noisier when these disclosures are present. Other findings indicate that the magnitude of estimation error and disclosure complexity play a role in the extent to which investors reduce their reliability perceptions in the presence of a CAE disclosure.

Thesis: S.M. in Management Research, Massachusetts Institute of Technology, Sloan School of Management, 2019
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 23-24).
In the post-crisis period substantial attention has been placed on regulation of exposures held off balance sheet by large banks. I analyze the effect on equity holders of such regulation. While requiring banks to hold capital against their on balance sheet exposures largely doses not perturb equity holder valuation capital held against off balance sheet exposures decreases the equity claim by generating a deleveraging effect when the balance sheet is expanded. Shareholders command a premium to compensate for the change in the value of their claim leading to a deviation of prices of redundant derivative claims from their replicating portfolios. Importantly, this effect does not appear under a standard capital ratio.
by William Goulding.
S.M. in Management Research
S.M.inManagementResearch Massachusetts Institute of Technology, Sloan School of Management

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1993.
Includes bibliographical references (leaf 107).
by Jonell Kerkhoff.
M.S.