Effect of different levels of supplementation after weaning on beef heifer development

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, supplementatio

Geographical influence of heat stress on milk production of Holstein dairy cattle on pasture in South Africa under current and future climatic conditions

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 inde

Investigating novelty traits to improve cow-calf efficiency in South African Afrikaner, Angus and Charolais for climate-smart production

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 weigh

Score and hide-thickness, together with tick burden and body condition score, in four cattle breeds in the South-eastern Free State province of South Africa

Published ArticleA study was conducted to determine the differences between four breeds in respect of coat score, hide-thickness, tick burden and body condition score. The study was comprised of 40 heifers - 10 of each breed, namely Afrikaner, Braford, Charolais and Drakensberger. A subjective system of coat scoring, ranging from extremely short to very woolly, was used. Body condition score was measured subjectively, with 1 being emaciated and 9 being obese. Hide-thickness (in mm) and tick count were also determined. Between August 2007 and early March 2008, measurements were carried out on the same 10 animals of each breed, with highly significant differences in body condition score, hide-thickness and tick count being observed between the breeds in all instances. Coat scores differed significantly between breeds in the earlier and latter stages of the study becoming less significant midway through. A significant difference in body condition score within breeds was also found, while hide-thickness did not differ significantly within breeds

A SURVEY OF LICK SUPPLEMENTATION AND MANAGEMENT PRACTICES OF COMMERCIAL BEEF FARMERS IN THE ZASTRON DISTRICT

Published ArticleA study was conducted to determine the supplementation and management practices of commercial beef farmers. 48 commercial farmers from the Zastron district were selected for this study out of a prospective of 60 farmers that were bona fide commercial farmers and members of Free State Agriculture. The farmers reported the following calving percentage ranges: one farmer (2.1%) between 50 and 59%, three farmers (6.3%) between 60 and 69%, 19 farmers between 70 and 79%, 22 farmers between 80 and 89% and three farmers between 90 and 99%. Preventative vaccination was common practice as only one farmer did not vaccinate any of his cattle (n = 48). The provision of supplements seemed to be general practice (100%, n = 48) in the district as all the farmers gave some form of supplementation to their cattle. Only 22.9% (n = 11) of the farmers provided supplements according to the production status of the animals and the main reason for not doing so is that 37.8% (n = 14) of the respondents believed that it complicated management and 18.9% (n = 7) thought it not necessary. It is believed that a lack of understanding of the function of supplements by some of the farmers in the district could be the cause of what could be considered as insufficient supplementation by animal nutritionists

The profitability and production of a beef herd on transitional Cymbopogon- Themeda veld, receiving three different levels of lick supplementation - Preliminary results

Published ArticleThe 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

Production and profitability of a beef herd on transitional Cymbopogon-Themeda veld receiving three levels of lick supplementation

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, performanc

Genetic studies on the South African Mutton Merino: growth traits

Genetic parameters were estimated for 36-, 42-, 50-, 100- and 150-day weight in the South African Mutton Merino breed. The direct heritability estimates obtained were 0.270, 0.366, 0.278, 0.185 and 0.115 respectively. The maternal heritability estimates for the respective weights were 0.494, 0.249, 0.129, 0.091 and 0.080. The correlation between the animal effects (direct and maternal) varied between -1.000 for 36-day weight to -0.376 for 150-day weight. Very little selection progress was made over the period (1980-1999) in the breed. (South African Journal of Animal Science, 2000, 30(3): 172-177

The effect of selection on genetic parameter estimates

A simulation study was carried out to investigate the effect of selection on the estimation of genetic parameters for butterfat production in dairy cattle. It was found that selection leads to a substantial overestimation of fixed effects and variance components and an underestimation of heritability estimates. This effect was attributed to the fact that all information on all animals in the analysis should be available to compensate for the effect of selection. (South African Journal of Animal Science, 2001, 31(2): 107-114

Genetic parameter estimates for type traits in the South African Jersey breed

Known environmental effects influencing type trait scores in South African Jersey cattle were identified. Variance components and heritabilities were estimated for these traits as well as genetic correlations among them and with production traits. Heritability estimates were generally low to medium. It is suggested that hoof and leg traits be excluded due to low estimated heritabilities and/or coefficients of variation. Genetic correlation estimates suggested that selection for production yield should improve most type traits and vice versa. Estimation of breeding values and fitting a multiple trait model is suggested. (South African Journal of Animal Science, 2000, 30(3): 186-192