Letteratura scientifica selezionata sul tema "Bonsmara cattle breeders"

AbstractCarcass traits of two indigenous African (Sanga) breeds (Afrikaner and Nguni), one indigenous African composite breed (Bonsmara), one foreign composite breed (Santa Gertrudis) and two continental European breeds (Brown Swiss and Pinzgauer) were compared. Treatment means were adjusted to the mean overall subcutaneous fat proportion (47 g/kg). Despite differences in maturity type, only the Afrikaner dressed out significantly (P < 0·05) lower than the foreign breeds. Both Sanga breeds and the Bonsmara had significantly higher muscle yields than the Santa Gertrudis and Pinzgauer, mainly due to the high intermuscular fat of the latter two breeds. When muscle yield was expressed per unit of bone, the Afrikaner and Bonsmara compared favourably with the larger breeds, due to their low bone and intermuscular fat yield, while the Nguni had a relatively high bone yield. The Santa Gertrudis had the lowest muscle yield due to its high bone and intermuscular fat yields, especially when compared with the smaller Bonsmara composite. Both Sanga breeds had significantly higher (P < 0·05) proportions of total weight, meat and bone (Afrikaner P > 0·05) in the high-priced cuts compared with the other breeds at the same subcutaneous fat level. Despite the statistical significance, differences were small in magnitude and probably of little commercial value. At the same time mean subcutaneous fat proportion, tissue yield and distribution patterns expected of late maturing breeds were observed for smaller indigenous breeds, suggesting that it was specific breed effects rather than maturity type effects, which were evident.

The major histocompatibility complex region has been implicated in explaining some of the variation observed in adaptability and tick susceptibility of cattle. The bovine leukocyte antigen region of 192 cattle representing indigenous, composite and exotic breeds used in commercial beef production in Namibia and South Africa was investigated using four microsatellite markers. Ticks counted under the tail were taken as an indicator of tick susceptibility. Tick scores of all but one population was low (11 to 20 ticks), with only the South African Bonsmara population having an average score of 31 to 40 ticks per animal. The observed variation based on four microsatellite markers ranged from 5.5 alleles in Namibian Afrikaner to 7.7 alleles in South African Nguni and Bonsmara cattle. Unbiased heterozygosity values ranged from 0.66 (Namibian Afrikaner) to 0.76 (South African Bonsmara). Structure analyses grouped the five populations into three indistinct clusters with limited genetic variation between the populations.

Subjective semen evaluation using standard optical microscopy is the most common practice. Semen parameters routinely assessed are volume, concentration, progressive motility, and morphology. However, computer-aided sperm analysis (CASA) represents an objective evaluation, sperm assessment that are reproducible and reliable. Such semen parameters have not been evaluated in Afrikaner, Brahman, and Bonsmara bulls’ semen. The present study evaluated the sperm motion and kinematics characteristics of semen from stud Afrikaner, Brahman, Bonsmara, and Nguni bulls using CASA technology. The electro-ejaculator was used for semen collection from Afrikaner (n = 11), Brahman (n = 7), Bonsmara (n = 10) and Nguni (n = 16) bulls of known and proven fertility. Semen was collected following 4 days of resting period. The bulls ranged between 5 and 6 years of age. After collection, the semen samples were immediately transferred to a thermo-flask and maintained at 37°C for further evaluation in the mobile laboratory (Nedambale, 2014). The CASA-Sperm Class Analyzer® system (Microptic, Barcelona, Spain) was used to evaluate sperm motion, velocity, and kinematic parameters or characteristics of raw/fresh semen from 4 cattle breeds. Data were analysed using GenStat® statistical programme (VSN International, Hemel Hempstead, United Kingdom). Treatment means were compared using one-way ANOVA. The total sperm motility rate was similar for all breeds: Afrikaner (92.2 ± 4.2), Brahman (90.7 ± 9.0), Bonsmara (93.9 ± 4.0), and Nguni (96.0 ± 2.7). However, Brahman and Afrikaner bull semen had higher sperm cells moving in a progressive motility of 57.3 and 45.6%, respectively, compared with other breeds (P < 0.05). Nguni, Afrikaner, and Bonsmara had the highest sperm cells moving in a rapid movement of 73.7, 72.4, and 67.4% (P > 0.05), respectively. The bulls sperm trajectories had a variation, as they were recorded to be irregular and not linear (P < 0.05). The straight-line sperm velocity (µm s−1), wobbling %, and amplitude of lateral head displacement % was similar for the 4 breeds (P > 0.05). In conclusion, CASA technology was a useful technique for assessing differences in sperm motion and kinematic (motility and velocity characteristics) among different bull breeds.

The sustainable use of water, or any other natural resource for that matter, is not the only factor that should be considered in terms of sustainability, as social equity and economic prosperity are equally important. The objective of this study was to analyse different breeds of beef cattle, following the same production method, in terms of their water footprint and economic value addition for different links in the value chain. A bottom-up approach was applied to identify the breed with the best economic water consumption in terms of beef production. The results indicated that the total WF/kg carcass revealed notable differences between the various breeds. The Bonsmara had the smallest WF/kg carcass, while the Limousin had the largest. The WF/kg of beef for the different cuts (rib eye, topside, and flank) showed large variations between the breeds and between the different cuts of beef from the same breed. In terms of the economic water consumption, the Angus consumed between 4% and 25% less water per rand of economic value addition than the Bonsmara, Simmentaler, Simbra, Limousin, Afrikaner, and Brahman. When the economic water consumption of the individual value links was considered, it was found that Bonsmara had the best figures for cow–calf production, while the Limousin and Simmentaler were the best in terms of feedlot finishing and processing, respectively. These contradicting results showed the importance of a bottom-up approach to ensure that the fallacy of division does not occur and, secondly, that possible problem areas in the value chain are identified and addressed separately.

The productive performance of progeny by Bonsmara and Belmont Red sires was compared in contemporarily reared groups in South Africa. Measurements on 4279 pedigreed progeny of 96 Bonsmara sires and 18 Belmont Red sires were recorded over 15 years in 4 diverse climatic regions of South Africa. Growth traits were measured on growing stock from birth to 18 months at pasture. Weight gain, feed conversion rate, frame size, scrotal circumference and visually assessed ‘functional efficiency’ scores were recorded on male progeny fed high protein rations. Carcass traits were measured on a subset of the male progeny. Age at first calving, and repeated measurements of calving date and calving interval were recorded on breeding females as indicators of reproductive performance. Tick counts were made on males and females across a range of ages during times of heavy field infestation. There were differences in progeny performance for some traits. Bonsmara sired animals generally scored higher than Belmont Red progeny for functional efficiency. Belmont Red sired calves were lighter at birth (35.9 v. 37.3; P0.05) and cows by Belmont Red sires had a shorter average calving interval (440 v. 455; P<0.05). Sire breed by region interaction was not important. The differences in scored and measured traits generally reflected differences in selection policies adopted by the breed societies. Variation in growth and fertility traits due to sire was greater than variation due to breed and demonstrated the potential for identifying superior individuals. The performance of the sire breeds for the range of traits and environments studied advocated that selected Bonsmara and Belmont Red animals from South African herds would be suitable for inclusion in breeding programs in Australian Belmont Red herds.

The collection of high numbers of oocytes for in vitro embryo production in the cow depends on the number of antral follicles available for aspirations. The number of antral follicles varies significantly among cows and can be estimated by ovarian ultrasonography or measurement of serum concentrations of antimullerian hormone (AMH). The AMH is secreted by the granulosa cells of small antral follicles and serum concentrations are independent of the stage of the oestrous cycle. Therefore, it may be useful as a tool to select oocyte donors for in vitro embryo production. An experiment was designed to evaluate the effect of breed of cattle and the correlation of serum AMH concentrations on the number of viable oocytes and embryos produced in vitro. Cumulus-oocyte complex were collected during 44 ultrasound-guided follicle aspiration sessions performed at random stages of the oestrous cycle without superstimulation in 14 Bonsmara, 11 Braford, and 19 Brangus cows that were used for commercial in vitro embryo production using frozen-thawed semen from bulls of the same breed. Blood samples were collected by jugular venipuncture at the time of OPU, centrifuged at 3000 × g for 30 min for serum separation which was frozen at –20°C until AMH analysis. Serum AMH was evaluated using an ELISA (AnshLabs, Webster, TX, USA). The sensitivity of the AMH assay was 0.011 ng mL–1 and intra-assay CV were <5%. The number of viable oocytes collected and embryos produced in each breed were compared by ANOVA and means were compared by the protected l.s.d. test when ANOVA revealed statistically significant differences. Regression analysis and Pearson correlation were used to determine the relationship between the number of viable oocytes aspirated and the number of embryos produced. The mean (± SEM) number of viable oocytes collected was greater (P < 0.05) from Brangus (23.3 ± 4.3) and Braford (22.5 ± 3.6) than from Bonsmara donors (12.2 ± 2.5). Although not statistically different, the numbers of embryos produced followed the same pattern (Brangus, 4.4 ± 0.9; Braford, 3.4 ± 0.6; Bonsmara, 2.9 ± 0.5). Serum AMH concentration was positively correlated with the number of viable oocytes collected in all breeds (R2 = 0.63 for Bonsmara, 0.50 for Braford, 0.32 for Brangus; P < 0.01). Serum AMH concentrations were also correlated with the number of embryos produced in all breeds (R2 = 0.32 for Bonsmara, 0.16 for Braford, 0.39 for Brangus). However, AMH concentrations were not significantly correlated with the proportion of viable oocytes collected and embryos produced. Results demonstrate a breed effect on the number of oocytes collected per session and that circulating AMH concentrations are correlated with the number of viable oocytes collected per session in commercial in vitro embryo production programs.

Context Indigenous cattle breeds represent an important genetic resource for livelihood of communal-area inhabitants. Indigenous breeds have the ability to withstand harsh climatic conditions, can adapt genetically to poor-quality forages and are resistant to parasites and diseases. These unique traits possessed by indigenous breeds are under threat because of unrestrained crossing with exotic commercial breeds, and this can lead to total loss of a breed. Aims The study was conducted to assess the genetic diversity and population structure of South African non-descript communal beef cattle populations by using 25 microsatellite markers. Methods Unrelated and non-descript animals (n = 150) were sampled from communal areas from five (5) provinces of South Africa, namely, Eastern Cape, KwaZulu–Natal, Limpopo, Mpumalanga and the North West, with 30 samples per breed taken. Six (6) known cattle breeds (n = 180) were used as a reference population. This included Angus, Afrikaner, Bonsmara, Brahman, Drakensberger and the Nguni, with 30 samples per breed. Key results High level of genetic diversity was found across the five non-descript populations, with an average heterozygosity of 75%. The Limpopo population was found to be the most diverse population, with the highest average number of alleles (8.5) and heterozygosity (ranging between observed heterozygosity of 70% and expected heterozygosity of 79%). STRUCTURE software assigned populations (2 ≤ K ≤ 20), with the most probable cluster being at K = 7. The Eastern Cape, KwaZulu–Natal and Limpopo populations had genetic material similar to those possessed by the Nguni and Bonsmara reference populations. Conclusions Results from the study showed that most genetic differentiation occurred within populations rather than among populations, and this might be due to the fact that there is no selection for or against any specific production trait expressed in the populations. Implications The obtained information will serve as a baseline for the development and implementation of sound breeding programs that will assist in controlling the gene flow, so as to lower the possible genetic dilution of the currently available genetic material.

Agriculture is responsible for 5% to 10% of the global anthropogenic greenhouse gas (GHG) emissions. Livestock contribute about 65% of agricultural GHG and enteric fermentation accounts for 90% of this. The global warming potential of CH4 is known to be 23 times more than that of carbon dioxide, resulting in it being a significant role player in the greenhouse gas family. The laser methane detector (LMD) is an instrument that has the potential to measure enteric CH4 emission from livestock under normal husbandry activities. This study was aimed at evaluating the efficiency and results, when using the LMD to measure CH4 production under normal production conditions. Twelve heifers, four each from the Bonsmara, Nguni and Jersey breeds, were subjected to grazing natural veld, forage sorghum under irrigation, oats pasture under irrigation or a total mixed ration. Measurements were taken late afternoon (18:00) when the animals were ruminating. Four repeated measurements, lasting 60 seconds each, were taken on 10 consecutive days on each of the production systems. The animals were adapted for a period of 14 days on the specific feed, before the measurements were taken. The Jersey heifers produced significantly less CH4 than the Bonsmara and Nguni on natural veld, with no significant differences between breeds on the forage sorghum. On natural veld the heifers generated 48% more CH4. These results thus indicate that the LMD produce sensible and repeatable measurements that can be interpreted in respect of CH4 production by cattle. The next step will be to increase the number of breeds, numbers per breed, and feeding strategies over all seasons in order to validate and build up a baseline data set on the use of the LMD to measure CH4 emissions from cattle under different grazing conditions.Keywords: Heifers, methane emission, pastures, total mixed ration

Genetic parameters were estimated for growth and fertility indicator traits in a South African beef cattle population. Measurements on 5601 pedigreed progeny of 96 Bonsmara sires, 18 Belmont Red sires and 20 Bonsmara × Belmont Red cross sires were recorded over 19 years in 4 diverse climatic regions of South Africa. Growth traits were measured on growing stock from birth to 18 months at pasture. Cow weights were measured at calving and weaning. Age at first calving, and repeated measurements of calving day and calving interval were recorded on 1993 breeding females as indicators of reproductive performance. The traits were analysed using univariate and bivariate animal models with maternal effects fitted. Direct heritability of growth traits (0.11–0.42) and female fertility traits (0.02–0.13) suggested that genetic progress could be made by selection for some traits. Genetic correlations between growth and fertility traits were variable (–0.47–0.85) and indicated that multi-trait selection would be the best method of dealing with multidirectional forces on productivity traits. Genetic correlations between direct and maternal effects on liveweight traits were mostly negative indicating that genetic improvement of traits with strong maternal influence, such as weaning weight, would be complicated and supported the use of post-weaning weights with less maternal influence as selection criteria to improve the direct additive component of growth. The genetic parameter estimates provide useful reference values for estimation of breeding values in a proposed combined-breed genetic evaluation program.

Several Breeders within the Bonsmara cattle breeders’ association have been selecting for polledness otherwise known as the trait for the genetic absence of horns. There are less costs associated with polled animals, as they require less management input than horned animals. International stud breeders are willing to pay a premium for Bonsmara stud animals certified as homozygous polled, and Bonsmara breeders therefore requested a study for the identification of polled status, using DNA markers. Several microsatellite markers were tested in a linkage analysis on a number of Bonsmara families originating from three polled herds. All of the markers tested in the final Twopoint linkage analysis showed significant linkage with the polled trait. This indicates that the current model proposed for the gene action of polledness is applicable to the Bonsmara breed. Furthermore, by using the Transmission disequilibrium test (TDT), an allele of one of these microsatellites was found to be strongly associated with the polled trait. Due to an inherent lack of phase-known, three-generation families, tracing this allele through the test pedigrees to determine polled status was not possible. These results indicate that phase-known family data must be available so that microsatellite markers linked to the Polled trait can be traced visually to differentiate homozygote polled animals from heterozygote polled animals. Microsatellite markers are a tool that can add additional information in the conclusive determination of Polled status, but cannot as yet be used in isolation to test for polledness in the South African Bonsmara breed. Copyright
Dissertation (MSc)--University of Pretoria, 2008.
Animal and Wildlife Sciences
unrestricted

The production environment is known to have a large influence on extensively managed beef cows. A better understanding of the relationship between the beef cow and her environment should be useful in the pursuit of improving beef cow efficiency. The influence of the production environment on the efficiency of extensively managed Bonsmara cows was investigated through a series of research objectives. It was found that VEGMAP’s bioregion classification system can be used to describe the South African beef production regions. The environmental characteristics with the potential to influence beef cow efficiency were identified as temperature, rainfall, cation exchange capacity, soil pH, soil organic carbon, soil P and grazing capacity. A dataset was created that contains the historical cow production records for every Bonsmara breeder. GIS tools were then used to link the cow production records with the production region in which the farm is located, as well as the environmental characteristics for that specific location. The combined dataset was then statistically analysed to investigate the research objectives. The influence of the geographic location, production region and breeder on Bonsmara production traits was investigated by cluster analysis and ANOVA. Results from ANOVA indicate that production region has a statistically significant (p < 0.05) influence on production traits. The influence of the breeders on the same production traits was, however, statistically much larger (p < 0.0001) than production region. Bonsmara production traits are therefore influenced to a greater extent by the breeders rather than production environment. Stepwise regression analysis was used to determine the influence of the combined environment on production traits. The combined environment has a statistically significant (p < 0.0001) influence on all the production traits. The results indicate that the extent of the influence of the environment on production change through the growth curve. The environment’s influence was the greatest at weaning (9%) and yearling age (10%). Bonsmara weaning and yearling weights therefore show the largest potential for manipulation through management. The influence of individual environmental characteristics on all the Bonsmara cow production traits was then investigated by the same stepwise regression analysis. Most of the environmental characteristics were found to have a statistically significant (p < 0.0001) influence on the production traits. Rainfall and temperature had the largest influence on Bonsmara production traits. The negative influence of rainfall was attributed to the influence of rainfall on the quality of the grazing. The influence of temperature on production traits was small. The small negative influence of temperature could indicate that Bonsmara cows are well adapted to the main South African beef production regions. Finally, the relationship between Bonsmara cow size and reproduction was investigated by linear regression analysis. Results indicate that larger Bonsmara cows are to some extent more reproductive than smaller cows. The study confirmed that production environment influences beef cow efficiency. Bonsmara breeders however have a much larger influence on the efficiency of their cows through the implementation of management practices and breeding objectives.
Dissertation (MSc(Agric))--University of Pretoria, 2012.
Animal and Wildlife Sciences
unrestricted

The study compares the biological performance of progenies of the Afrikaner x Western Sanga crossbred (small frame) and the Bonsmara (medium frame) cattle on the following traits: calving and growth rates as well as mortalities. The study was conducted in the Sourish Mixed Bushveld of the North West province. The objective was to identify a lowcare cattle breed, which can withstand unfavourable conditions under which most farmers in the North West Province operate. The results of this study indicated that, under good management, the Bonsmara cattle have higher growth rates compared to the Sanga cattle. There were statistical differences with regards to birth, pre-wean and wean masses, (P< 0.0001). Sanga cattle however were able to maintain higher calving rates under all varying conditions (Bonsmara 77% average and Sanga 84% average). The Sanga, due to its lower nutritional requirements, on average requires 15% less of the surface area required by the Bonsmara. Sanga cattle also returned better yields in terms of kilogram weaned calf per LSU and per hectare. With regard to herd mortalities, there was no significant difference (P = 0.03329).