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Breeding of beef cattle is changing, with more emphasis on efficiency of production. Feed cost is the highest expense, and reducing it has the potential to increase profitability. Common measures of efficiency are ratio traits such as feed conversion (feed consumed/weight gain) and feed efficiency (weight gain / feed consumed). Feed conversion ratio is commonly used in South Africa in an attempt to improve feed efficiency. These ratio traits are associated with growth rate. Selection for them would result in higher growth as a correlated response and might also increase the mature size of the cows and their maintenance cost. Thus, alternative efficiency traits such as residual feed intake and residual daily gain have been proposed. In this study, variance components, and genetic parameters for feedlot traits for the South African Simmentaler breed were estimated, with emphasis on the efficiency traits. The focus was to evaluate the use of residual feed intake as an alternative trait. The results indicate non-significant correlations between residual feed intake and body weight and growth traits, implying that residual feed intake should have little effect on the other traits. This is in contrast to the moderate to strong correlations of feed conversion ratio with the same traits. The study demonstrates that considerable genetic variation exists for residual feed intake, which can be exploited. Selection for residual feed intake can reduce the carbon footprint of beef due to the associated lower methane emissions.

Individual and maternal breed additive effects and heterosis exist for most economically important traits in cattle. Crossbreeding may therefore be valuable for emerging and commercial beef farmers in improving the productivity of their herds. Calves were produced by mating Afrikaner, Bonsmara and Nguni cows to Afrikaner, Bonsmara, Nguni, Angus and Simmental bulls. The cows used were from Vaalharts Research Station or were purchased from other herds. Data were collected over three years. Individual and maternal additive effects and individual heterosis were estimated simultaneously as continuous linear variates. The estimated genetic effects were then used to predict production levels that may be achieved through implementation of top-cross, two-breed rotation, and terminal sire crossbreeding systems. The individual estimates of the genetic effects were relatively small and in most cases were not different from zero, with the exception of the maternal additive effects of Nguni on preweaning traits and their individual additive effect on cow weight, which were less than those of Bonsmara. However, the alternative crossbreeding systems differed across traits. The straight-bred breeding system was least efficient, followed by the crisscross system (+2%) and the terminal sire system that utilized Simmental (+4%), with the terminal sire system utilizing Angus being on average most efficient (+8%). The inter-generational genetic differences in cow weight that resulted from the use of different breeds of sire increased its standard deviation by 5 to 6% in rotational crossing. Despite the relatively small magnitude of the genetic effects, advantages of crossbreeding systems became evident.Keywords: breed additive, crossbreeding, heterosis, post-weaning, pre-weaning

Wet carcass syndrome (WCS), which is observed predominantly in sheep, affects carcass quality negatively. After slaughter the carcass appears to be ‘wet’ with a subcutaneous accumulation of watery fluid. Not all animals in a contemporary group are afflicted, and experimental attempts to induce WCS have been unsuccessful. The reported prevalence of WCS in Dorper and Dorper crosses gave rise to the hypothesis that it may have a genetic basis. Therefore, the primary objective of this investigation was to test this hypothesis using a high-density SNP assay to search loci that may predispose sheep to WCS. Muscle samples from 43 afflicted and 41 unafflicted sheep were collected from slaughterhouses in the province of Northern Cape, South Africa, and in southern Namibia. Tests against candidate genes proved uninformative, as did runs of homozygosity. Potential associations between WCS and an autosomal genetic marker were investigated further in a case-control genome-wide association study. Separate analyses for each sex were motivated because single nucleotide polymorphisms (SNPs) on the X chromosome suggested quantitative trait loci. These analyses revealed significant associations between SNP and WCS in males, but not in females. Three SNPs that reached genome-wide significance in males are in strong linkage disequilibrium with the Duchenne muscular dystrophy, 5-hydroxytryptamine receptor 2C, and Teneurin transmembrane protein 1 genes. These genes are identified as positional candidate genes, and the Duchenne muscular dystrophy, 5-hydroxytryptamine receptor 2C genes have biological effects that have been documented in other species, making them plausible functional candidate genes for WCS in sheep.Keywords: association analysis, Dorper, sheep carcass, single nucleotide polymorphisms, X chromosome

The purpose of the study was to identify a cost-effective supplementation regimen to rear replacement heifers on transitional Cymbopogon-Themeda veld. A total of 120 Drakensberger heifers aged 6 - 7 months were randomly allocated to three supplementary treatment groups from 2011 - 2014. A three-phase supplementation programme was used while the production year was divided into three periods, namely summer (wet season) (approximately mid-December to March), winter (early dry season) (April to July), and late winter (late dry season) (August to approximately mid-December). The late winter treatments consisted of three levels of supplemental crude protein (CP), a percentage of protein derived from non-protein nitrogen (NPN) and metabolizable energy (ME), namely T1: 306 g CP/kg (47.4% NPN) + ME 7.4 MJ/kg; T2: 329 g CP/kg (70.72% NPN) + ME 6.89 MJ/kg; and T3: 475 g CP/kg (95.86% NPN) + ME 2.4 MJ/kg. In summer, T1 was supplemented with 164 g CP/kg (7% NPN) + ME 9 MJ/kg + 13 g P/kg; T2 with Voermol Superfos with 150 g CP/kg (13.6% NPN), ME 0 MJ/kg, and 50 g P/kg; T3: 0 g CP/kg, ME 0 MJ/kg, and 60 g P/kg. The traits were nutrient intake, supplement cost, mean bodyweight, weight gains/losses and mean BCS. The study concluded that feeding replacement heifers to traditional bodyweight increased development costs without improving production sufficiently. Veld that is in good condition together with a mineral (60 g P/kg) supplement in the wet season and a protein and mineral supplement (96% NPN) in the dry season gives the highest economic return. Keywords: beef heifers, post wean, supplementation

Genetic variability within and between breeds allows adaptation to a changing environment and consequently prepares producers for the future. Eleven bovine-specific microsatellite markers were used to genotype animals from each of nine South African cattle breeds: Afrikaner (N = 550), Angus (N = 550), Bonsmara (N = 550), Boran (N = 321), Brahman (N = 550), Drakensberger (N = 550), Nguni (N = 550), Simmental (N = 550), and Tuli (N = 311). These breeds were drawn from Bos taurus africanus, Bos taurus, and Bos indicus. Genetic variability estimates included unbiased heterozygosity, effective number of alleles, and inbreeding. Ranges of these parameters were 0.569–0.741, 8.818–11.455, and − 0.001–0.050, respectively. Breed private allele and breed pairwise comparison was also used to characterize the breeds. The analysis of population structure with K = 2 revealed clusters comprised of Sanga-indicine and taurine, while K = 3 included separate clusters of Sanga, indicine, and taurine, and with K = 9 showed the breeds arising from unique progenitor populations. This study broke new ground in molecular cattle genetic diversity by genotyping a large sample size per breed and using a larger number of breeds compared with similar studies that have been conducted in the recent past which have either used a smaller number of breeds or smaller sample sizes but with a larger number of marker loci. Thus, opportunities that arise to explore genetic diversity and relationships in both the livestock and wildlife industries in Southern Africa may capitalize on microsatellite marker databases which remain cost-effective and accessible due to their extensive use for parentage verification.

The aim is of the study was to identify novelty traits that could be used as breeding objectives to improve cow-calf efficiency and describe cow efficiency in extensive systems in support of climate-smart production in beef cattle. The traits that were investigated were ‘weaning weight of the calf as a trait of the dam’ (K205) and ‘kilogram calf weaned per large stock unit’ (KgC/LSU. The latter trait is a value that expresses performance (calf weaning weight) per constant unit, namely per LSU. This may be a useful breeding objective or goal to increase production efficiency, which may reduce the carbon footprint of extensive beef cow-calf production systems. The investigation of the novel traits was conducted on three diverse breeds, namely Afrikaner, Angus and Charolais, with 6104, 7581 and 2291 complete cow-calf records, respectively. Only cows with all three first parities recorded were used to investigate KgC/LSU and K205, as breeding objectives to improve cow-calf efficiency. The heritabilities for KgC/LSU were 0.52, 0.24 and 0.21 for the Afrikaner, Angus and Charolais, respectively, and for K205 were 0.40, 0.17 and 0.13 respectively. The genetic relationship between KgC/LSU and K205 for Angus and Charolais varied substantially. In Charolais cows a strong negative correlation (-0.75) was found, while a strong positive correlation (+0.84) was estimated in Angus cows. These results indicate that a ‘cow efficiency index’ in which several traits (production, fertility and efficiency) are included may be a more effective alternative breeding strategy. Breeding strategies and production systems to improve the production efficiency of beef cattle could play a significant role in reducing the carbon footprint and would enhance climate-smart beef production. Keywords: breeding objective, calf weight, cow weight

In most extensive beef production systems in South Africa, calves are weaned at specific dates. This implies that cows that calve late in the season wean younger and lighter calves. In the current study, Bonsmara cows were mated naturally after synchronization over six years (2009 - 2014) in an extensive production system on natural veld in the Central Bushveld bioregion. Within the herd, 50% of cows were synchronized prior to the commencement of the summer breeding season and they were mated naturally for 90 days. The results indicated that calving rate did not differ significantly between cows that were synchronized and non- synchronized. However, there was a significant difference between years in calving rate. Oestrous synchronization prior to natural breeding influenced the average days to conception. The difference in percentage of cows that calved within 293 days of the onset of the breeding season between those that were oestrous synchronized and non-synchronized was 15% in favour of the synchronized cows. Although calves from synchronized cows achieved higher average weaning weights, the cost implications of synchronization offset the benefit of higher calf weights. Keywords: calving rate, oestrous synchronization, natural breeding

The purpose of the study was to gain insight into the genetic variability of the Letelle sheep breed, a breed that has been managed as a closed population for 90 years, with no new genetic material being permitted into the breed. The Letelle is a South African developed dual-purpose sheep breed and is classified as a Merino type with a Spanish Merino origin. The breed exhibits good fine wool characteristics and yields high-quality mutton. Line-breeding, family-breeding, and inbreeding are applied, and multiple sire matings are practised to prevent a sire from having a large influence on the national flock. Ear samples were collected from 10 animals each from 10 commercial and 11 seed-stock flocks and genotyped using 17 microsatellite markers. Unbiased heterozygosity ranged from 0.58 to 0.68 and the observed heterozygosity from 0.52 to 0.65. The estimated effective population size (N e ) was 228.2 - 321.9. Results from analysis of molecular variance (AMOVA), a Bayesian assignment test, and a neighbour-joining (NJ) tree suggested that no genetic sub-structure existed within this population and that the seed-stock and commercial flocks could be regarded as one genetic population. The average within flock (F IS ) and within breed (F IT ) inbreeding coefficients were 10.1% and 14.5%, respectively. Despite the level of inbreeding, levels of genetic diversity were moderate and potentially provide opportunities for future selection and adaptation. Further testing could identify flocks in which conservation management is required as well as those with high genetic variability, which would provide the best reservoir for selection to adapt to future climatic challenges. Keywords: genetic distance, inbreeding, microsatellite markers, population structure

It is important that climate smart beef production systems are developed and put in place to reduce the GHG production from beef and to mitigate the effects of climate change on beef production. An effective way to reduce the carbon (and water) footprint from beef is to reduce the animal numbers and increase the production per animal, thereby improving their productivity. Increased productivity generates less GHG emissions per unit of livestock product. With the recent research developments surprisingly, efficiency of production has been neglected. Cow-calf efficiency can be defined as kg calf weaned per Large Stock Unit (KgC/LSU) mated. The LSU is linked to daily feed requirements. Using this definition of cow efficiency, it was estimated that there was an increase of 18.3%, 10.0%, 14.2% and 10.4% in cow efficiency of the indigenous Afrikaner, Bonsmara, Drakensberger and Nguni respectively over a period of 33 years, as a result of breeding and management. In South Africa the enteric methane emissions factor (MEF(enteric)), is defined as kg methane/year of a LSU is approximately 94 kg /LSU/year for beef cattle. In the case of the Afrikaner, the MEF(enteric) was 1 kg per kilogram calf weaned in 1980 and it decreased to 0.88kg in 2013, a decrease of 12%. Likewise the MEF(enteric) decreased by 6.6%, 9.3% and 6.6% in the case of Bonsmara, Drakensberger and Nguni breeds respectively. These results indicate that cow productivity can be improved if the weaning weight of the calf relative to the weight of the cow can be increased; and the fertility improved consequently reducing production of greenhouse gases from the South African landrace breeds. It is therefore important to develop breeding objectives to improve cow calf efficiency of the South African landrace and other breeds.

The purpose of the study was to investigate the effects of three levels of lick supplementation on the production and reproduction of cows grazing transitional Cymbopogon-Themeda veld. The study was conducted over three years (2011–2014). A total of 150 Drakensberger cows were randomly allocated to three supplementary treatment groups. These supplementation formulations are available commercially and are typical of levels used under farming conditions. In summer Treatment 1 (T1) consisted of a supplement containing 50 g phosphate (P)/kg and 150 g crude protein (CP)/kg. T2 and T3 both consisted of supplements containing 60 g P/kg and 0 g CP/kg. In winter, T1 consisted of a supplement containing 367 g CP/kg, 77.5% non-protein nitrogen (NPN) and metabolizable energy (ME) content of 5.25 MJ/kg. T2 had 466 g CP/kg, 88.7% NPN and a ME content of 4.4 MJ/kg. T3 had 475 g CP/kg, 95.9% NPN and an ME content of 2.4 MJ/kg. Traits were calf birth weight, 100-day and weaning weights of calves, cow weight at weaning, inter-calving period (ICP), conception rate and body condition score (BCS) of cows. Calf birth weight was affected by supplementation treatment only in year 3 and 100-day weight in year 2. However, weaning weight and reproductive performance were not influenced by treatment. It was concluded that the level of supplementation of each treatment group enabled the cows to operate within their target weight range; however, it was more profitable to use the T3 supplementation option. Keywords: Cymbopogon-Themeda veld, cows, performance

The Afrikaner is one of three indigenous cattle breeds found in South Africa. Afrikaner cattle were originally extensively used for crossbreeding purposes and breed development. The objective of this study was to determine the genetic diversity of selected stud and commercial herds from the whole South African Afrikaner population, as well as to determine the genetic structure among these herds. Assignment methods (based on STRUCTURE software) revealed a real structure consisting of four genetic populations (K = 4). Estimates of genetic diversity did not support the hypothesis of significant loss of genetic diversity in any individual Afrikaner herd. Heterozygosity estimates ranged from 0.456 - 0.737 within individual populations, with an overall heterozygosity estimate of 0.568 for the Afrikaner breed. The average number of alleles per locus was regarded as being 2.67 - 7.78, with an average of 5.18 alleles per locus. It could be concluded that a moderate to high degree of variation is still present within the Afrikaner cattle breed, despite the recent decline in numbers of this indigenous breed.Keywords: Bos taurus africanus, heterozygosity, inbreeding, microsatellite markers

The purpose of the study was to investigate a possible genotype by environment interaction in first calf South African Holstein cows for both production and reproduction traits. Data from 100 975 cows on a total mixed ration (TMR) and 22 083 pasture based cows were used. These cows were the progeny of 4 391 sires and 84 935 dams produced over a period of 11 generations. Traits analysed were milk production (corrected to a 305-day equivalent) and age at first calving (AFC). Both were recorded over a period of 30 years from 1980 - 2010. Production or AFC in each environment (TMR vs. pasture) was treated as a separate trait. Bivariate analyses, fitting an animal model using the ASREML software, were used to obtain genetic correlations between the traits measured in each environment. The fixed factors included were a concatenation of breeder-keeper-year for both milk production and AFC and age at first calving which was fitted as a linear regression for milk production. The random part consisted of the direct additive effects only. The genetic correlation for milk production measured in the two different environments was 0.90 (0.027) and that of age at first calving 0.28 (0.12). The heritability estimates for milk production were 0.23 (0.008) under the TMR system and 0.32 (0.015) for the pasture based system, while the estimates for AFC were 0.063 (0.005) and 0.055 (0.009), respectively. The rather large-scale effect in the heritability (0.23 → 0.32), as well as the correlation of less than one for milk production between the two environments, indicates that a G x E may exist. However, the low genetic correlation between the two environments for AFC is much more real and indicates that G x E should be taken into account when sire selection is performed.Keywords: Age at first calving, milk production, total mixed ration, pasture

The purpose of this study was to evaluate alternative expressions of genetic merit for cow efficiency. Weights of Pinzgauer cattle taken at birth, weaning, and maturity were extracted from the South African National Database. Average daily gain from birth to weaning (ADG) and cow weight (CWT) were analyzed with a multi-trait mixed model. The model included direct and maternal genetic effects, a permanent environmental effect attributable to dams on ADG, a direct genetic effect and a permanent environmental effect attributable to there being multiple observations from the same cow on CWT as random effects. Heritability estimates for direct and maternal additive effects on ADG were 0.27 ± 0.04 and 0.06 ± 0.02, respectively. The estimated heritability for CWT was 0.45 ± 0.06. Estimates of repeatability for ADG and CWT were 0.42 and 0.67, respectively. Estimated breeding values based on the preceding results and using the maternal genetic effect on ADG as a proxy for the direct genetic effect on milk production were combined in six indexes of cow efficiency. These indexes sought to increase output and decrease input simultaneously, to increase output holding input constantly, and to hold input constant while decreasing input. The diversity of emphasis applied across these indexes suggests the need for due diligence in developing breeding objectives for improvement of cow efficiency. Indexes that are consistent with the econometric definition of efficiency and seek to simultaneously increase output and reduce input are recommended. ______________________________________________________________________________________ Keywords : genetic parameters, multiple trait selection, Pinzgauer, selection index

relationship between L1 and the general Hereford population recorded by the AHA. In a second experiment, 5 sets of 400 animals were drawn from the AHA herdbook representing each year from 1980 to 2008 and pseudo mated to L1 sires and their relationship to L1 calculated as described above. Over the period, the number of animals recorded by the AHA that were related to L1 increased by 1.69 ± 0.07% per year. The L1 Hereford population was ancestral to 79% of Hereford cattle recorded in 2006 through 2008. The greatest concentration of animals related to L1 was in the Great Plains and eastern Corn Belt of the United States, but animals related to L1 were found in 48 states. In a third experiment, 240 L1 Hereford cattle and 311 sires representative of the Hereford breed in the United States were genotyped using the Illumina BovineSNP50 BeadChip. Resulting genotypes were used to assess the probability that the animals sampled from the U.S. population were members of L1. The average probability of membership in L1 was 0.20 and the regression of genomic probability of membership on pedigree relationship was 1.73 ± 0.11 (r = 0.65). These results document the far-reaching and profound impact of a long-term research program.

The wildlife industry in South Africa has shown immense growth since the 1990s, which was brought about by the private game segment of the industry. In recent years, trophy quality Cape buffalo breeding animals have achieved extremely high prices. Much of the economic value of these animals can be attributed to horn size, which is important for breeding and hunting purposes. The main objective of the study was to estimate variance components for horn traits of economic importance as well as to develop guidelines for recording these traits. To date, no quantitative genetic analysis has been done for any traits in Cape buffalo. The total number of horn measurement records included in the evaluation was n = 945 for outer spread (BHSO), n = 470 for tip to tip (BHTSCI), n = 468 for left boss and n = 479 for right boss. For descriptive statistics, males and females were considered separately while age was divided into clusters of six months. A multi-trait animal model using Monte Carlo Markov Chains methods was used for the estimation of genetic parameters. Results suggest that it is not economically viable to measure horn spread and tip to tip of females after 48 months of age. Horns of the males continue to grow beyond 91 months of age. Boss records were unreliable owing to the applied measurement techniques for female and young animals. An inbreeding coefficient of 0.008 was calculated, suggesting adequate genetic diversity in the studied population. The heritability estimates of the horn traits were low, showing that extreme care has to be taken to develop effective selection programmes for the buffalo game industry using their horn genetic parameters. Further quantitative studies are required to support the results of the current study. Keywords: genetic correlation, genetic parameters, heritability, Monte Carlo Markov Chain

Much of the economic value of wildlife can be attributed to horn size, which is an important trait for trophy hunters. The main objective of the study was to estimate genetic parameters for the economically important horn traits of sable antelope that are currently being measured in the South African industry. To date, no quantitative genetic analysis has been done for any traits in sable antelope. The total number of records included in the evaluation were n = 1713 for horn length (SHL), n = 1503 for circumference (SHC), n = 1486 for tip to tip (SHTT), n = 1505 for tip length (SHT), and n = 1447 for rings (SHR). Males and females were considered separately in six-month age clusters. A Markov chain Monte Carlo (MCMC) multi-trait analysis was used to estimate (co)variance parameters for the horn traits. The results indicate a sex effect for all the traits and suggest that it is not economically viable to measure horn length of either sex after 54 months old. The horns of females are on average 40% shorter compared with bulls at maturity. Continuous horn growth throughout the lifetime of sable is suggested by the formation of ring posts, but is often masked by horn attrition and inadequate measuring techniques. An inbreeding coefficient of 0.0043 suggests adequate genetic diversity in the studied population. Heritability estimates of horn traits varied from 0.085 to 0.52, while genetic correlations ranged from 0.1 to 0.6 with the highest correlation being found between horn length and tip to tip. Further studies are recommended to confirm these results. Keywords: Game, genetic evaluation, heritability

The Afrikaner is an indigenous South African breed of "Sanga" type beef cattle along with breeds such as the Drakensberger and Nguni. Six composite breeds have been developed from crosses with the Afrikaner. Additionally, Afrikaner has been the base from which exotic breeds were established in South Africa through backcrossing. The study examined genetic diversity of Afrikaner cattle by genotyping 1257 animals from 27 herds in different geographic areas of South Africa and Namibia using 11 microsatellite markers. Multiple-locus assignment, performed using the Bayesian clustering algorithm of STRUCTURE, revealed three underlying genotypic groups. These groups were not geographically localized. Across herds and markers, the proportion of unbiased heterozygosity ranged from 0.49 to 0.72 averaging 0.57; mean number of alleles per locus ranged from 3.18 to 7.09, averaging 4.81; and allelic richness ranged from 2.35 to 3.38, averaging 2.67. It is concluded that a low inbreeding level of 2.7% and a moderate to high degree of variation still persists within the Afrikaner cattle breed, despite the recent decline in numbers of animals.

Heat stress, as a consequence of global warming, can have a profound effect on dairy cattle in South Africa. In this paper, current milk production data of Holstein dairy herds on pasture in South Africa, together with climate variables related to heat stress, were used to model and identify geographical areas for optimal milk production under current and future climatic conditions. To model the influence of heat stress on milk production of Holstein dairy herds on pasture in South Africa, the maximum entropy (Maxent) modelling technique was used in a novel approach to model and map optimal milk-producing areas. Geographical locations of farms with top milk-producing Holstein herds on pasture were used as presence-only data points. Only three of a possible eight climate variables that made significant contributions to the model were included, namely evaporation rate, relative humidity and mean annual temperature. The modelling technique showed good capability to capture the geographical influence of heat stress on milk production of Holstein dairy cattle and to reconstruct this relationship in sites where no data were available. The method performed well with low test omission rates, an area under curve (AUC) value of 0.929, and mean training data predictive rate of 0.66 (SD = 0.13). The modelled map indicated optimal milk production areas in the eastern parts of South Africa, which correlates well with the geographical influence of heat stress as represented by the temperature humidity index for the country. Future climate change projections (2046–2065) were used to predict optimal milk-producing areas for the future, indicating progressive shrinking of currently suitable areas and a geographical shift towards the southern parts of the east coast of South Africa. Possible long-term viable alternatives are suggested, including changes in nutrition and replacing existing breeds with more heat tolerant genotypes. Keywords: climate change, climate variables, Maxent modelling, temperature-humidity index

The objective of this study was to assess the reproductive performance of two Nguni ecotypes (Nguni and Landim) raised in a subtropical environment to enhance strategies for livestock development and restocking programmes within the southern African region. Reproduction data collected between 1996 and 2009 from 365 cows of the Landim and Nguni ecotypes were analysed. From the results, ecotype, place of birth, year and season of birth/calving had significant effects on age at first calving (AFC) and calving interval (CI). Overall means for AFC and CI were 1,071 ± 166 days and 432 ± 85 days, respectively, while average calving rate was 88.0 ± 4.7%. Heifers born in the dry season had lower AFC than heifers born in the wet season. Heifers born at Impaputo Breeding Center were the youngest at first calving, followed by the South African born ones. Heifers of the Landim ecotype also calved younger than heifers of the Nguni ecotype. CI was shorter in wet seasons (main breeding seasons) than in dry seasons. Interaction between ecotype and year–season (p < 0.005) showed that, in wet and dry seasons, Nguni cows had shorter CI than the Landim. This study demonstrates for the first time a possible genotype-by-environment interaction between Nguni ecotypes. This might aid future cattle development and restocking programmes in southern Africa taking into consideration the adaptation of indigenous genotypes and climate change.

A total of 84% of South Africa’s land is available for agriculture, of which 13% is cultivated and 71% is only suitable for extensive livestock farming. Beef cattle farming is dominating these areas. The type of production strategy to be followed, e.g. purebreeding with adapted genotypes or crossbreeding, will depend primarily on the environment and level of management. A crossbreeding project with specialized sire lines (Angus and Simmentaler) and dam breed bulls, mated to Afrikaner, Bonsmara and Nguni females (mated in all possible combinations) is being conducted in Northern Cape, producing 15 genotypes. The climate is semi-arid, characterized by hot summers (average maximum temperature 32°C) and cold winters (average lowest temperature –0.5°C), with an annual rainfall is 440 millimeters. The 5 bull breeds are mated to 8 females from each of the breeds. The mating season is from 15 December until 28 February. Predicted means of Afrikaner, Bonsmara, and Nguni calves for preweaning traits, and for dam weight at weaning of their calves, corrected to 7 years of age for the first three seasons are reported. At birth, Nguni calves weighed less (32.9kg ± 0.6), than either Afrikaner (36.0 ± 0.9) or Bonsmara (37.3 ± 0.7) calves. The respective 205-day corrected weaning weights for the different breeds were (192.0kg ± 9.0) for the Afrikaner; (218. ± 13.0) for the Bonsmara and (185. ± 6.0) for Nguni. The cow weight of the Nguni (365.0kg ± 7.0) was significantly different from that of the Afrikaner (446.0kg ± 10.0) and Bonsmara (454.0kg ± 10.0). Performances of the calves sired by the various breeds of sire varied from 187. ± 7.0 in Afrikaner x Nguni to 224. ± 13.0 in Angus x Bonsmara. A study to estimate all the crossbreeding effects on cow efficiency and component traits is currently underway.

Seven indigenous chicken populations were identified and characterized from four administrative zones in northwest Ethiopia. A total of three hundred chickens were characterized under field conditions for qualitative and quantitative traits following standard chicken descriptors. Large phenotypic variability among chicken populations was observed for plumage color. About 25.49, 22.3, and 16.4 % of the chickens have white, grayish and red plumage colors, respectively. The rest showed a considerable heterogeneity like black, multicolor, black with white tips, red brownish and white with red striped plumage colors. The following characteristics were also displayed: plain head shape (51.18%), yellow shank color (64.42%) and pea comb (50.72%). About 97.52% of the chickens did not have feathers on their legs. Variations were also observed on quantitative characters such as shank length, egg size and body weight and other reproductive traits characterized on intensive management system.

Surveys using both purposive and random sampling methods was carried out in four zones of north-west Ethiopia to describe the village-based poultry production systems and constraints in order to design future improvement and conservation strategies. The majority of the respondents were female (74.16%). This indicated that most of the time the women, whether in male-headed or female-headed households, are responsible for chicken rearing while the men are responsible for crop cultivation and other off-farm activities. About 99% of the respondents gave supplementary feeds to their chickens. Almost all farmers provided night shelter for their chickens, in part of the kitchen (1.36%), in the main house (39.07%), in hand-woven baskets (7.29%), in bamboo cages (1.51%) or in a separate shed purpose-made for chickens (50.77%). The major causes of death of chickens during the study were seasonal outbreaks of Newcastle disease (locally known as fengele) and predation. It is important to collect and conserve local poultry breeds before they are fully replaced by the so-called improved breeds. As most of the poultry production is managed by women, focusing on training and education of women will enable not only the improvement of poultry production but also family planning and the overall living standards of the family and the community.

The objective of this experiment was to assess the reproductive and productive performance of Nguni cattle distributed among 11 farms in four regions of South Africa. Only data of registered Appendix A to Stud Proper Nguni animals from the Agricultural Research Council of South Africa’s database were used. Data were collected from 2061 dams and 3285 calves between 1990 and 2009. Overall means for age at first calving (AFC) and calving intervals (CI) were 33.79 ± 4.90 months and 400.29 ± 78.70 days, respectively. Dry season-born heifers had lower AFC than wet season-born heifers. Dry seasons 4 and wet seasons 1 had lower CI than seasons 2 and 3, indicating that conceptions take place between December and May. Average growth weights of calves were 24.87 ± 3.13, 151.91 ± 21.09, 169.25 ± 23.68 and 237.96 ± 27.34 kg at birth (BW), weaning (WW), 12 months (YW) and 18 months of age, respectively. BW was higher in dry seasons 4 and wet seasons 1; WW and YW were higher in dry than in wet seasons. This is the first study demonstrating that performance of Nguni cattle is influenced by ecological regions of the dam’s origin, year-season of birth/calving, breeder’s management, parity and herdbook status, confirming that environment-genotype interactions influence the performance of Nguni cattle in southern Africa. This stimulated a follow-up study on the use of geographic information systems to specifically identify factors influencing the reproductive and productive performance of Nguni cattle in southern Africa.

Estimates of co(variance) components were obtained for weights at birth, weaning and 6, 9 and 12 months of age in Muzaffarnagari sheep maintained at the Central Institute for Research on Goats, Makhdoom, Mathura, India, over a period of 28 years (1976 to 2003). Records of 5530 lambs out of 169 rams and 1631 ewes were used for the study. Analyses were carried out by restricted maximum likelihood (REML), fitting six animal models, including various combinations of maternal effects. Heritability estimates for weight at birth, weaning and 6, 9 and 12 months of age were 0·09, 0·21, 0·06, 0·10 and 0·14, respectively. Maternal heritability of body weight declined from 0·07 at birth to 0·02 at weaning. The maternal permanent environmental component contributed 10 to 11% to the total variance for all traits except weight at 12 months. A significant large negative genetic correlation was observed between direct and maternal genetic effects on weaning weight, suggesting the presence of antagonistic environmental, as well as perhaps genetic, effects in daughter and dam. Results suggest that maternal additive effects were only important in early stages of growth, whereas a permanent environmental maternal effect existed at all ages up to 9 months, probably as a carry-over effect of maternal influences present at weaning. Modest rates of genetic progress appear possible for all weights, but the presence of an antagonism between direct and maternal effects on weaning weight would complicate attempts to improve both by selection.

Genetic parameters and (co)variance components were estimated for weight at birth and at 15, 30, 45, 60 and 75 days of age for a flock of Muzaffarnagari sheep maintained at the Central Institute for Research on Goats, Makhdoom, Mathura over a period of 27 years (1976–2002). Records on 5201 lambs descended from 1568 ewes and 170 rams were included in the analysis. Analyses were carried out by REML fitting an animal model and ignoring or including maternal genetic or permanent environmental effects. Six different animal models were fitted for all traits, and the best model was chosen after testing improvements in log-likelihood values. Direct heritability estimates were inflated substantially for all traits when maternal effects were ignored. Direct heritability estimates were 0.08 ± 0.02 for birth weight and 0.02 ± 0.02, 0.02 ± 0.02, 0.27 ± 0.08, 0.09 ± 0.04, and 0.29 ± 0.08 for weights at 15, 30, 45, 60, and 75 days, respectively. Maternal genetic effects contributed only 4 to 8% of the total phenotypic variance from birth to 30 days of age, and this effect diminished further with increasing age. Maternal heritability was low for pre-weaning growth traits and should have only a small effect on selection response. Estimates of the fraction of variance due to maternal permanent environmental effects were 0.09 ± 0.02, 0.15 ± 0.04, 0.12 ± 0.03, 0.11 ± 0.04, 0.14 ± 0.02, and 0.08 ± 0.04 for body weights at birth and at 15, 30, 45, 60, and 75 days, respectively. These results indicate that selecting for improved maternal and/or direct effects in Muzaffarnagari sheep would generate only slow genetic progress in early growth traits.

In this study the serum testosterone levels of 177 Dorper rams participating in the Free State ram performance testing scheme were determined and correlated to certain phenotypic traits, body measurements and growth performance. All rams were managed extensively on natural pastures. Serum testosterone levels showed a positive correlation (P

In this study, the influence of two feeding regimes on certain reproductive characteristics of young Dorper rams was investigated. Thirty-two Dorper rams were divided into two homogeneous groups. Rams in the first group ( n =16), 472.5±8.0 days old were fed ad libitum intensively on a diet (9.5 MJ ME/kg DM and 12.5% protein) for 7 weeks, while the second group ( n =16), 460.6±8.5-day-old rams were maintained on natural pastures and received lick supplementation (100 g/animal per day) with 16% CP, 8 MJ ME/kg DM and 10% fibre for a similar period of time. At the end of the trial period, semen was collected by electro-ejaculation from each ram and evaluated, prior to the slaughtering of the rams. Following slaughter, the scrotums were excised and dissected. Seminal, scrotal, testicular and carcass characteristics of rams from both groups were compared. Nutritional management had an influence on scrotal circumference, scrotal weight, scrotal fat, testes weight and volume. Significant greater scrotal circumference (SC) were recorded in the intensively managed (IM) rams (34.1±0.4 cm) compared to the extensively managed (EM) rams (31.8±0.6 cm) and significantly more fat deposits (particularly in the scrotal neck) were found on the IM rams (109.1±8.7 g) when compared to the EM rams (45.4±6.5 g). Significant differences between the IM (50.1±3.8% and 2.3±0.3) and EM (80.5±2.3% and 3.3±0.2) rams were observed for overall motility ( P P

Summary Breed additive and non-additive effects plus heritabilities and repeatabilities for milk yield per lactation (LMY), milk yield per day (DMY), lactation length (LL), annual milk yield (AMY), annual milk yield per metabolic body weight (AMYBW) and cow weight at calving (BW) were estimated for 5464 lactation records collected from purebred Boran (B), Friesian (F), and crosses of Friesian and Jersey (J) breeds with the Boran breed raised in the tropical highlands of Ethiopia. Single trait analysis was carried out by using two equivalent repeatability animal models. In the first model the genotype was fitted as a fixed group effect, while in the second model the genotype was substituted by breed additive, heterotic and recombination effects fitted as fixed covariates. Both the F and J breed additive effects, measured as a deviation from the B breed were significant (p 0.05) for BW. The heterotic contributions to the crossbred performance were also positive and significant (p

Variance components and direct and maternal heritabilities were estimated for weight at birth ( n =4960), weaning at 180 days ( n =4250) and yearling at 365 days ( n =3330) and preweaning average daily gain ( n =4250). Data were from calves of purebred ( Bos indicus ) Boran, Barca and Horro and their crosses with Friesian, Jersey and Simmental breeds that were separated from their dams 1 day after birth and fed milk from a bucket. Data were analysed using six alternative animal models (direct and including or excluding maternal associated effects). Direct heritability estimates from the best model for each trait were: 0.14±0.03 for birth weight, 0.08±0.03 for weaning weight, 0.06±0.02 for preweaning average daily gain and 0.13±0.03 for yearling weight. Direct maternal heritability estimates were small and significantly different from zero for only birth weight (0.07±0.02), weaning weight (0.04±0.02) and preweaning average daily gain (0.04±0.02). Direct genetic correlations between birth weight and the other three traits were: 0.66±0.08, 0.55±0.19, 0.50±0.12 with weaning weight, preweaning average daily gain and yearling weight, respectively. The genetic correlation between weaning weight, preweaning average daily gain and yearling weight was high and ranged from 0.82±0.11 to 0.97±0.01. Small, but nonzero maternal heritabilities estimated for weaning and preweaning average daily gain for artificially reared calves in this study should be interpreted cautiously because of the potential bias from unaccounted breed additive and nonadditive effects in the dam. Results of this study also showed that estimates of variance components and genetic parameters suitable for general use can be obtained from mixed purebred and crossbred data after appropriately accounting for breed additive and nonadditive effects.

Summary In an effort to estimate breed differences, heterotic and recombination effects, a total of 4957 birth weight (BWT), 4245 weaning weight (WWT) and 3330 yearling weight (YWT) records collected from 38 crossbred and three purebred genotypes generated from crossing Friesian (F), Jersey (J) and Simmental (S) with the Boran (Bo), Barca (Ba) and Horro (Ho) (Bos indicus) breeds in Ethiopia were used. Differences between genotypes were significant (p 0.05) and −2.3 ± 0.6 kg for BWT, 8.82.1, 11.8 ± 2.3 and 13.7 ± 2.4 kg for WWT, 60.4 ± 11.3, 64.8 ± 12.3 and 90.6 ± 12.7 g for ADG, and 19.8 ± 2.6, 19.5 ± 2.8 and 20.8 ± 2.9 kg for YWT, respectively. The recombination effects were significant (p 0.05) and −16.0 ± 4.0 kg for WWT, −88.0 ± 17.1, −39.4 ± 18.4 and −102.2 ± 21.3 g for ADG, and −14.4 ± 4.0, −0.1 ± 4.4 (p > 0.05) and −17.5 ± 4.9 kg for YWT, respectively. It could be concluded that the breed differences, heterotic and recombination effects seem to be important genetic factors affecting early growth performances in the breed crosses tested. Zusammenfassung Fruhe Wachstumsleistungen von Bos taurus × Bos indicus Kreuzungen in Athiopien: Schatzung individueller Kreuzungseffekte Um Rasseunterschiede, Heterosis und Rekombinationseffekte zu schatzen, wurde ein Datensatz mit insgesamt 4957 Geburtsgewichten (BWT), 4245 Absetzgewichten (WWT) und 3330 Jahrlingsgewichten (YWT) verwendet, die an 38 Kreuzungsgenotypen, hervorgegangen aus Kreuzungen der Rassen Friesian (F), Jersey (J) und Simmental (S) mit Boran (Bo), Barca (Ba) und Horro (Ho) (Bos indicus), sowie an 3 Reinzuchtgenotypen in Athiopien erfasst wurden. Die Unterschiede zwischen den Genotypen erwiesen sich fur alle Merkmale signifikant (p 0,05) und −2,3 ± 0,6 kg fur BWT, 8,8 ± 2,1, 11,8 ± 2,3 und 13,7 ± 2,4 kg fur WWT, 60,4 ± 11,3, 64,8 ± 12,3 und 90,6 ± 12,7 g fur ADG sowie 19,8 ± 2,6, 19,5 ± 2,8 und 20,8 ± 2,9 kg fur YWT. Die Rekombinationseffekte waren signifikant (p 0,05) und −16,0 ± 4,0 kg fur WWT, −88,0 ± 17,0, −39,4 ± 18,4 und −102,2 ± 21,3 g fur ADG sowie −14,4 ± 4,0, −0,1 ± 4,4 (p > 0,05) und −17,5 ± 4,9 kg fur YWT. Es kann der Schluss gezogen werden, dass Rasseunterschiede, Heterosis und Rekombinationseffekte wichtige genetische Faktoren hinsichtlich fruher Wachstumsleistungen in den untersuchten Rassekreuzungen sein konnen.

Summary Five genetic models were evaluated for goodness-of-fit and estimation of crossbreeding parameters using 41 genotypes produced from crossing three Bos taurus (Friesian, Jersey and Simmental) with three Bos indicus (Boran, Barca and Horro) breeds. The traits used for testing of the models were birth weight, weaning weight, pre-weaning-average daily gain and yearling weight. These models were: (1) Dominance model, (2) Dickerson's model (recombination loss) (3) Additive × dominance interaction model, (4) Dominance × dominance interaction model and (5) Kinghorn's model (x). Models 2–5 are epistatic models that included all effects in model one plus one type of epistatic interaction based on a two-locus gene model. All five models tested, provided high levels of fit, with adjusted R2 values averaging 93% over traits. All the epistatic models fit the data significantly (p

The importance of containing costs through the optimal utilization of feed emphasizes the need to optimize, rather than maximize, the rate of reproduction. It is, however, unknown which lick supplementation regimen, provided to an extensive beef herd on mixed veld, could bring about the most profitable and efficient farming enterprise. The aim of the study was thus to determine what lick supplementation regime would be most profitable in an extensive beef production system maintained on transitional Cymbopogon-Themeda veld. The different lick supplementation regimens offered differed in crude protein (CP) content, percentage non-degradable protein (NDP), metabolisable energy (ME) content, and recommended daily intake. A herd of Drakensberger cows and heifers was divided into three treatment groups (Treatment A, Treatment B and Treatment C), with 70 animals (n = 70) per treatment group. The CP, NDP, ME content of the licks provided in Treatment A were higher than those provided in Treatment B and C, while the CP, NDP, ME content of the licks provided in Treatment B were higher than those provided to Treatment C, but lower than those provided to Treatment A. The first two years’ (2011 - 2012 and 2012 - 2013) preliminary results indicate no significant differences in parameters that affect cow herd performance (weaning weight, cow herd pregnancy rate, intercalving period) between treatments. However, substantial cost differences in the lick supplied between treatments was recorded; thus, affecting profitability. Significant differences between treatments in the pregnancy rates of the first-calf heifers was recorded in the second year, and indicated that providing protein in a drought during summer to first calf heifers may increase the calving rate and hence profitability.Keywords: Beef cattle, cow herd production, extensive farming, lick supplementation, profitability

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

Primary beef cattle farming in South Africa is largely extensive, whereas dairy farming is based on both total mixed ration and pasture production systems. Under natural rangeland conditions, decomposition of manure is aerobic, which produces carbon dioxide (CO2), part of which is absorbed by the regrowth of vegetation rather than released into the atmosphere, and water (H2O) as end products. Thus the cow releases methane (CH4) and the manure CO2. This is in contrast to intensive cow-calf systems in large parts of Europe and North America, where large quantities of manure are stockpiled and undergo anaerobic decomposition and produce CH4. Thus both the cow and the manure release CH4, which result in a higher carbon footprint than the extensive cow-calf systems. In dairy farming, increasing cow efficiency through intensive feeding (same kg milk output by fewer animals) can reduce farm CH4 production by up to 15%. In addition, when differences in productivity are accounted for, pasture systems require more resources (land, feed, water, etc.) per unit of milk produced and the carbon footprint is greater than that of intensive systems. This raises the question as to why the carbon footprint of intensive dairy cow production systems is less, but the carbon footprint of intensive beef cow-calf production systems is higher. The explanation lies in the differences in production levels. In the case of beef cows the weight of the intensive cows will be ± 30% higher than that of the extensive cows, and the weaning weight of their calves will also differ by ± 30%. In the case of dairy cows the weight of the intensive cows will be ± 20% higher, but their milk production will be ± 60% higher. The higher increase in production (milk) of intensive dairy cows, compared to the increase in production (calf weight) of intensive beef cows, explains the antagonism in the carbon footprint between different beef and dairy production systems. Unfortunately, carbon sequestration estimates have been neglected and thus the quantitative effects of these differences are not known.Keywords: Cow-calf production, methane, pasture production, production levels, total mixed ration

Climate change represents a feedback-loop in which livestock production both contributes to the problem and suffers from the consequences. The impact of global warming and continued, uncontrolled release of greenhouse gasses (GHG) has twofold implications for the livestock industry, and consequently food security. Firstly, the continuous increase in ambient temperature is predicted to have a direct effect on the animal, as well as on food and nutrition security, due to changes associated with temperature itself, relative humidity, rainfall distribution in time and space, altered disease distribution, changes in the ecosystem and biome composition. Secondly, the responsibility of livestock production is to limit the release of greenhouse gases (GHG) or the carbon footprint, in order to ensure future sustainability. This can be done by implementing new or adapted climate-smart production systems, the use of known and new technologies to turn waste into assets, and by promoting sustainable human diets with low environmental impacts. The following elements, which are related to livestock production and climate change, are discussed in this paper: (1) restoring the value of grasslands/rangelands, (2) pastoral risk management and decision support systems, (3) improved production efficiency, (4) global warming and sustainable livestock production, (5) the disentanglement between food and nutritional needs, focusing on nutrient rich core foods, (6) GHG from livestock and carbon sequestration, and (7) water and waste management. No single organization (or industry) within South Africa can perform this research and the implementation thereof on its own. The establishment of a (virtual) centre of excellence in climate-smart livestock production and the environment for the livestock industries, with the objective to share research expertise and information, build capacity and conduct research and development studies, should be a priority.Keywords: Food and nutrition, global warming, production efficiency, rangeland, water, waste

The influence of cytoplasmic effects on weaning weight (WW) and age at first calving (AFC) were investigated in the South African Afrikaner beef breed. A total of 14 535 AFC records (1974 - 2008) and 68 152 WW records (1974 - 2011) were used in the estimation of variance components. All cows were assigned to different damlines, using the pedigree information available. The model used for WW include direct additive, maternal additive, the covariance between the animal-, permanent maternal environmental-, herd-year-season x sire- and damline effects, while the simplest model which include only direct- and damline effects were used for AFC. The contribution of the cytoplasmic effects to the total variance was negligible (less than 0.5%) for both traits. These results suggest that cytoplasmic effects can be ignored in genetic evaluations of Afrikaner cattle for the traits investigated.Keywords: Age at first calving, beef cattle, damline, weaning weight

Beef cattle are unique, because they not only suffer from climate change, but they also contribute to climate change through the emission of greenhouse gases (GHG). Mitigation and adaptation strategies are therefore needed. An effective way to reduce the carbon footprint from beef cattle would be to reduce the numbers and increase the production per animal, thereby improving their productivity. Sustainable crossbreeding systems can be an effective way to reduce GHG, as it has been shown to increase production. There are a wide range of different cattle breeds in South Africa which can be optimally utilized for effective and sustainable crossbreeding. This paper reports on the effects of crossbreeding on the kilogram calf weaned per Large Stock Unit (kgC/LSU) for 29 genotypes. These genotypes were formed by crossing Afrikaner (A) cows with Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) bulls and by back-crossing the F1 cows to the sire lines. A LSU is the equivalent of an ox of 450 kg with a daily weight gain of 500 g on grass pastures with a mean digestible energy (DE) content of 55% and a requirement of 75 MJ metabolizable energy (ME). Crossbreeding with A as dam line increased the kgC/LSU on average by 8 kg (+6%) - with the CA cross producing the most kgC/LSU (+8%) above that of the AA. The BA dam in crosses with C, H and S, increased kgC/LSU on average by 26 kg (+18%) above that of the AA dam, with the H x BA cross, producing the most kgC/LSU (+21%). The BA, CA, HA and SA F1 dam lines, back-crossed to the sire line breeds, increased kgC/LSU on average by 30 kg (21%), 21 kg (15%), 19kg (13%) and 26 kg (18%) above the that of the AA, respectively. The big differences between breeds in kgC/LSU provide the opportunity to facilitate effective crossbreeding that can be useful in the era of climate change. From this study it is clear that cow productivity can be increased by up to 21% through properly designed, sustainable crossbreeding systems, thereby reducing the carbon footprint of beef production.Keywords: Carbon footprint, cow productivity, kilogram calf, production systems

The objective of this study was to assess the effect of place of birth on the reproductive performance of two Nguni ecotypes (Nguni and Landim) raised in a sub-tropical environment to enhance strategies for livestock development and restocking programmes within the southern African region. Reproduction data collected between 1994 and 2009 from 301 cows of the Landim (n = 122) and Nguni (n = 179) ecotypes were analysed. Results indicated that ecotype and place of birth had significant effects on age at first calving (AFC) and calving interval (CI). The means for AFC were 1085 and 1003 days, those for CI were 422 and 436 days, while the calving rate (CR) was 90.0% and 85.7% for the Nguni and Landim, respectively. This study demonstrates for the first time a possible genotype by environment interaction between Nguni ecotypes. This might aid future cattle development and restocking programmes in southern Africa, taking into consideration the adaptation of indigenous genotypes and climate change. Keywords : Age at first calving, calving interval, ecotypes, Landim, environment

The goal of this research was to document the influence of Line 1 Hereford cattle, developed by the United States Department of Agriculture at its research facility in Miles City, Montana, on Hereford cattle in South Africa. Analytical approaches made use of both recorded pedigree and microsatellite marker information. Cattle with recorded performance data in South Africa were mated with Line 1 Hereford sires in silico and inbreeding coefficients were calculated for the resulting progeny. The relationship between South African and Line 1 Hereford cattle populations was estimated as twice the maximum inbreeding coefficient for the progeny of each South African animal. The calculated pedigree relationship of Hereford cattle registered in South Africa with Line 1 was 24%. Thirty-six South African Hereford cattle and a sample of 64 Line 1 animals were genotyped with 34 microsatellite markers. Based on a Bayesian model-based clustering method, the probability that the South African Hereford cattle were members of Line 1 was 0.38 ± 0.08. This research documents one aspect of the far reaching effects of the Line 1 Hereford population.Keywords: Gene flow, migration, relationship

The objective of this study was to discern opportunities for improving leather-making properties of hides originating from beef production systems based on indigenous Afrikaner cattle via crossbreeding. Data were previously unpublished breed means from purebred Afrikaner, Brahman, Charolais, Hereford and Simmental, top-crosses of Brahman, Charolais, Hereford, and Simmental sires on (1) Afrikaner dams producing F1 progenies and (2) Brahman × Afrikaner, Charolais × Afrikaner, Hereford × Afrikaner, and Simmental × Afrikaner F1 females producing both backcross and three-breed cross progenies. Hide yield (%), leather yield (dm2/kg), force 20% extension (Mpa), extension grain crack (%), extension break (%), force break (Mpa), slit tear force (N/mm), distension grain crack (%), and force grain crack (N/mm) were evaluated. Breed direct effects and individual heterosis, but not maternal effects, may be important for most of these traits. Direct effects due to the exotic breeds reduced hide yield but generally improved leather properties relative to the indigenous Afrikaner. For both hide and leather yields, individual heterosis effects arose primarily from indicus × taurus crosses with the Hereford × Brahman effect being most pronounced. Thus, there may be opportunities to improve leather yield and quality through crossbreeding relative to the straightbred Afrikaner. A top-cross mating plan may be recommended to enhance production by subsistence level farmers having access to Afrikaner females, provided that management can ensure appropriate use of the terminal sires.

Global warming is predicted to have a profound effect on livestock production in developing countries. An improved understanding of the adaptation of livestock to such changing production environments is thus important, but the measurement of adaptation is complex and difficult. Proxy-indicators for adaptation, such as reproductive and production traits, however, can be used. Livestock industries have a responsibility to reduce the release of greenhouse gases (i.e. the carbon footprint) and water use (i.e. the water footprint). An effective way of decreasing the carbon and water footprints from livestock is to reduce livestock numbers and increase the production per animal. Increased production generates less greenhouse gas emissions per unit of livestock product. Proper definition of breeding objectives and trait definition is essential in implementing efficient breeding systems to cope with climate change. Sophisticated statistical models continue to support animal breeding and improvement, especially with respect to production traits. Traits linked to fertility and survival are still problematic and appropriate genetic technology to properly characterize these traits needs to be developed. Gene or marker-assisted selection may play an important role in selection for disease and parasite resistance or tolerance, since it is generally difficult to measure these traits directly. Strategies that utilize breeding values derived from genomic analyses may speed up the process of breeding animals with higher and more efficient production and that are adapted to the changing environments as a result of global warming. However, both genetic and epigenetic controls influence genetic expression and should be taken into account when formulating breeding programmes. Subsistence farmers keep livestock for multiple purposes and the formulation of breeding objectives/strategies will have to consider these dynamics. Keywords: Breeding objectives, epigenetics, genomics, production systems, quantitative breeding, residual efficiency traits

A combination of multiple trait and repeatability models were used to estimate genetic parameters for birth weight (BW), weaning weight (WW), yearling weight (YW), eighteen month weight (FW) and three measurements of mature weight (MW) using 23 768 records obtained from the South African Brangus Cattle Breed Society. The data covered a period of 7 generations from 1985 to 2010. Direct heritability estimates obtained were 0.21 ± 0.024, 0.23 ± 0.021, 0.22 ± 0.025, 0.29 ± 0.029 and 0.24 ± 0.019 for BW, WW, YW, FW and MW, respectively. Maternal heritability estimates for birth weight and weaning weight were 0.05 ± 0.01 and 0.11 ± 0.001, respectively. The direct genetic correlations between the different traits were all positive, ranging from moderate (0.43 ± 0.081) between YW and MW to high (0.99 ± 0.043) between WW and FW.Keywords: (Co)variance components and ratios, repeatability models, South African Brangus cattle

The aim of the study was to investigate some population parameters, including generation interval, inbreeding and effective population size of Brangus cattle in South Africa (SA) to assist in constructing an effective selection programme for the SA Brangus breed. Pedigree analysis can describe the genetic variability and change over time, making it an important tool to be used to assess parameters like generation interval, inbreeding, effective population size and number of animals selected against number born. These traits can be used to make more informed selection decisions in order to maintain a genetically healthy population through a better understanding of the dynamics within the population. A Population Structure- and Pedigree Analysis Report was generated with the PopReport programme from the Institute of Farm Animal Genetics (FLI) with a Brangus datafile containing 65 536 animals. Results were reported for the time period of 1986 to 2008 and the following results were obtained: 3-generation pedigree completeness is at 73.8% for 2008, with an inbreeding coefficient of 1.39% and an annual increase in inbreeding of 0.058%. Weighted generation interval was 5.17 years and the effective population size based on the average inbreeding was 166.7 animals. Keywords: Pedigree analysis, Brangus, inbreeding

Direct- and maternal heritabilities were estimated for weight traits in Brangus cattle using random regression models. After editing, 54 924 records, from birth- (BW) to mature weight (MW) from 21 673 animals were selected for analysis. The data, which covered a period of 8 generations (1985 to 2010), were transformed to a log scale to accommodate the wide range of weights being studied (15 to 850 kg). Traits included in the analysis were birth- (BW), weaning- (WW), yearling- (YW), eighteen month- (FW) and three measurements of mature weight (MW). Linear polynomials with intercepts were fitted using random regression models. The direct heritability estimates were moderate and ranged from 0.13 to 0.25 while maternal heritability estimates were low ranging from 0.05 to 0.06.Keywords: Heritability estimates, South African Brangus cattle

A study was done to determine which factors had the greatest influence on a heifer’s susceptibility to heat stress. Parameters tested were breed, coat colour, coat score, hide thickness, weight gain, respiration rate and body condition score. The study was conducted in the southeastern Free State. Afrikaner, Bonsmara, Braford, Charolais, Drakensberger and Simmentaler heifers were subjected to a heat tolerance trial. A total of 60 heifers, 10 of each breed were evaluated. Rectal temperature (Tre) was used as a parameter to determine heat stress. The heifers were evaluated on 10 days, at 14:00 during the winter of 2007 and on seventeen days, at 14:00 during the summer of 2007/8 (after 1 h in the sun, no access to shade). In winter a significant difference in rectal temperature Tre between breeds was measured on seven occasions. Phenotypical factors tested for did not affect Tre in winter. In summer significant differences in Tre were measured on 12 occasions between breeds. The following factors had a significant influence on Tre in the following breeds: Afrikaner – hide thickness, Bonsmara – hide thickness, Charolais – coat score.

Economic values of milk volume (VOL), fat yield (FYLD), protein yield (PYLD), live weight (LWT), longevity (LON), calving interval (CIV) and somatic cell score (SCS) were derived for Holstein and Jersey cattle, based on milk payment systems of four major milk buyers in South Africa. The economic value of somatic cell score was calculated for only two of the payment systems. A bio-economic model was used to calculate economic values by determining changes in profit arising from an independent unit increase in each trait. Economic values for VOL, FYLD and PYLD varied substantially among the payment systems; particularly PYLD which ranged from ZAR 7.62/kg to ZAR 21.88/kg. Payment systems that do not pay for milk volume resulted in a negative economic value (-ZAR 0.49/l) for VOL. Live weight and CIV had constant economic values across payment systems (-ZAR 6.62/kg and -ZAR 5.75/day for Holstein and -ZAR 7.49/kg and -ZAR 4.19/day for Jersey, respectively, for LWT and CIV). Economic value of LON varied slightly with payment system (ZAR 1.09/day to ZAR 1.23/day in the Jersey and ZAR 3.59/day to ZAR 3.68/day in the Holstein). The economic value of SCS differed substantially between the two payment systems and was higher in the Holstein (-ZAR 949.26/score and -ZAR 1795.57/score) than in the Jersey (-ZAR 433.87/score and -ZAR 912.90/score). Relative emphasis of traits in the breeding objectives for South African dairy cattle should take due cognisance of the diversity in milk payment systems.

A study was conducted to compare mature cow weight in the South African Simmental population when defined as the weight of the cow at calving or the weight of the cow at weaning of the calf. Data included in the analysis were 14458 records for cow weight at calving (CWT-C) representing 6534 cows and 18871 records for cow weight at weaning (CWT-W) representing 8395 cows. All cows were born between 1968 and 1996, while all calves were born between 1977 and 1998. The following effects had a significant influence on the traits and were included in the genetic analysis: Cow age in years fitted as a covariate term (linear and quadratic) and contemporary group fitted as a fixed effect. Contemporary group was defined as the unique combination of herd, birth year of calf, month of weighing, breeder-defined management group code for the calf and supplementary feeding code for the cow (for CWT-W). All analyses were done using ASREML, first fitting uni-trait and then bi-variate animal models that made provision for up to four weights per cow. The estimated genetic correlation obtained between the two cow weight traits was 0.95 ± 0.03, with a residual correlation of 0.61 ± 0.02. The heritability estimates for CWT-C and CWT-W from this analysis were 0.29 ± 0.04 and 0.37 ± 0.04, respectively. From a breeding perspective, these results confirm that little benefit is to be gained from weighing cows at calving if cows are to be weighed at weaning. If cow weights are to be recorded for an indication of cow maintenance costs, then weight at weaning is the more reliable and practical measure to record. Keywords: Simmental cattle, mature cow weight

h',n: 0.17,0.29,0.14. The results indicate the importance of both permanent maternal environment and herdyear-season by sire interaction in the estimation of the genetic parameters. The exclusion of herd-year-season by sire interaction could lead to a serious overestimation of the direct additive components. The same applies for permanent maternal environment. The exclusion of this factor could lead to a serious overestimation of the maternal components. Both these factors should therefore be included in the across-herd weaning weight analysis of Bonsmara cattle. Speengewig rekords van 24 758 Bonsmarakalwers, die nageslag van 503 bulle uit 30 kuddes gebore vanaf 1980 tot 1993, is gebruik om die invloed van die insluiting van kudde-jaar-seisoen by vaar interaksie op die beraming van die genetiese parameters te ondersoek. Drie aparte modelle is gebruik in die DFREML analise van die data. In die eerste is permanente maternale omgewingseffekte ingesluit as 'n addisionele toevallige effek. Permanente maternale omgewingseffekte is in die tweede model vervang met kudde-jaar-seisoen by vaar interaksie. In die derde model is beide die faktore as addisionele toevallige effekte ingeluit. Die beramings van die (ko)variansie komponente en oorerflikhede vir direk additief (a), maternaal additief (m) en addisionele toevallige effekte vir die drie modelle gebruik in die analise was soos vo^lg: (o2": 138.04,65.23, 67.46; (o2r: 84.77,143.8b, 66.83; (oam: -57.47 , -28.24: -21.97; (o2per ^: 73.72, 71 .01; (o2Hvsrsi 41 .79, 41 .39; (o2": 251 .31',"274.78, 265.97; (o'o: 490.37,497.35,49 0.74;h'^:0.28,0. 13, 0.14;h'^:0.17,0. 29,0.14. Die resultate dui op die belangrikheid van beide die twee addisionele toevallige effekte in die beraming van die genetiese parameters. Die uitsluiting van kudde-jaar-seisoen by vaar interaksie kan lei tot 'n ernstige oorberaming van die direk additiewe komponente. Dieselfde geld vir permanente maternale omgewing. Die uitsluiting van die effek kan weer op sy beurt lei tot 'n oorberaming van die maternaal additiewe komponente, Beide die effekte behoort dus ingesluit te word in

No Abstract.