A study conducted by Dr Japie van der Westhuizen and his colleagues at SA Stud Book reveals just how important – and more profitable – it is to have appropriate breeding goals, and to meet them, in a commercial beef production herd. On the right side of Table 1 are the figures for a 100-breeding cow herd that achieves 90% calving, with the calves weighing an average
of 47% of their dam’s weight at seven months.
The statistics on the left-hand side are what Van der Westhuizen describes as “probably closer to the national average” in terms of productivity and profitability of commercial beef herds. Here, the herd achieves a 60% calving rate and the calves weigh an average of 40% of their dam’s weight.
“What I tried to show with this table – and I’m not a nutritionist or pasture expert – is that the total value of all calves that can be sold at R15,25/ kg liveweight is R309 000 on the right-hand side and R174 000 on the left side,” he explains. “If one considers the dry matter (DM) eaten collectively by the 100 breeding females of these calves to maintain themselves, the wastage on the right-hand side herd is 43t DM/year, while for the left-hand-side herd it’s 263t DM/ year. So there’s a huge difference between the inherent efficiencies of these two systems and others like them.”
The contributing factors to these differences include the cows’ fertility and the survivability of the calves, adds Van der Westhuizen. Fitness traits have a major impact on the efficiency of cow/calf production. Milk production is another contributing factor, therefore reproduction and maternal ability are two important traits to be considered when selecting genetics for a commercial beef production herd. Beef animals also have phenotypical traits, including the maturity type and muscling, and the way a particular animal performs under specific production conditions.
Genetics and blup values
The most important equation in animal breeding in a commercial beef production herd is: phenotypic variation = genotypic variation + variation caused by the environment (P = G + E). “This equation means that if one measures something on a commercial beef animal, or any other breeding animal for that matter, the results will be different between measured animals. This is due to the impact that the production environment has on the measured trait and the genetic differences between the various measured animals on the specific farm,” says Van der Westhuizen.
As environmental effects are not transferable to the next generation, the focus should be on genetics in this equation, because animals with top-notch genetic merit can transfer their genes to the next generation. When assessing the genetic merit of an animal, a cattleman should consider several aspects and then use the results to generate best linear unbiased prediction (BLUP) breeding values. BLUP values are partly due to an animal’s performance relative to contemporaries subjected to the same environmental conditions.
Add heritability (part of the differences in performance influenced by the transferable genetic differences), and these predictions are a true reflection of the expected response in the next generation.“It’s all well and good to select breeding animals based on single genetic traits, but sometimes it’s also necessary to evaluate a combination of traits during the selection process to generate more profit for the enterprise,” says Van der Westhuizen
Breeding value and progeny
The ‘breeding value’ of an animal is its value as a parent – the genetic merit of the animal and how the performance of
its progeny differs from that of other sires or dams. It is best to predict an animal’s breeding value as early as possible; this ensures more informed cow selection or bull purchase decisions. In order to make these decisions properly, the producer must compare the measurements, parentage and performance results of the animal with those of other animals under similar environmental conditions.
It is the responsibility of the stud breeding industry to make this information available, says Van der Westhuizen. “Even though a commercial beef producer is not a stud breeder, he should still measure the individual performances of his own animals to ensure that they meet the standards set for the industry,” he stresses.
Aspects to be measured include the reproduction rate and the value of the marketable products in terms of weaning weights. These on-farm measurements will also help the cattleman to make informed decisions on which animals to keep or cull. Animals purchased as replacements must be selected on their
BLUP values and not on aspects such as how heavy they are, or on the calving interval of the dam. “Basing purchase decisions on BLUP values favours the genetic merit of the animal and not the environment in which the animal was kept,” says Van der Westhuizen.
Different systems, different priorities
A problem often faced by the commercial cattleman is the discrepancy between the value of traits for certain production systems or along the production chain. A feedlot and a grass-fed producer, for example, might consider different traits important (see Table 2). The producer will not compromise on reproduction and cow efficiency, but these traits are unimportant to a feedlot, which emphasises growth efficiency, post-weaning growth weight and carcass dressing-out percentage instead.
This aside, according to Van der Westhuizen, the profile of an efficient commercial beef cow will include the following aspects:
- Low birth weight and easy calving
- The ability to produce enough good quality milk for pre-weaning growth;
- Good post-weaning growth before she has first bred to a bull;
- Marketable progeny that show good growth efficiencies in the feedlot;
- A maturity type suited to the production environment;
- Ideally, the proven ability to produce good female progeny that can be retained as replacement breeding females.
Phone Dr Japie van der Westhuizen on 082 332 9923 or email [email protected].