Genetic improvement in commercial and stud herds in Southern Africa

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Genetic change is driven by the efficiency of selection in the stud populations. Progress in the commercial sector will follow.

Estimated reading time: 5 minutes

In any population, genetic change is driven by the efficiency of selection in the stud populations. Progress in the commercial sector will, if they utilise information such as breeding values provided in the stud industry, follow the trend. In short, the commercial sector basically depends on the objectives and selection decisions made in the stud industry. It is therefore vital that both these sectors invest in proper record-keeping.

Record-keeping drives genetic improvement in the stud industry, but is also vital for the assessment of the results of the utilisation of genetic material from the stud sector, as well as the profitability of the commercial sector. This is especially relevant when new sires are purchased. A cow will only have one calf per year, while a sire can father numerous offspring. A good or bad sire can therefore have a drastic impact on the genetic makeup of a herd.

Selection using estimated breeding values (EBVs) for production traits has seen much success in both commercial and stud herds in Southern Africa. However, due to shifts in the global environment some often overlooked traits, not traditionally connected to production, are becoming more and more relevant – specifically traits related to climate change, labour, input costs and consumer preferences.

Adaptation to the environment

The average worldwide temperature has increased by approximately 0,7°C in the last century (Cassandro, 2020). Agricultural practices, especially livestock farming, is increasingly indicated as both a contributing factor and a potential victim of climate change.

The expected impact of climate change is an increase in the vulnerability of livestock systems (Gill and Smith, 2008), affecting livestock production in mostly four ways: availability and price of grain and other feedstuffs; quality and quantity of pastures and forage crop production; changes in the distribution of livestock diseases and parasites; and the direct effects of weather and extreme events on animal health, growth and reproduction (Smith et al., 1996).

The emphasis on selection for increased production in the past in many cases resulted in an increase in metabolic heat production, which in turn resulted in the animals being more susceptible to heat stress (Bernabucci et al., 2010). In tropical areas, the process of natural selection increased the animal’s ability to tolerate heat stress, which in turn had an influence on the appearance of the animal (Renaudeau et al., 2012). Adaptation to heat also included the ability to grow and reproduce in the presence of inadequate seasonal pasture, as well as increased parasite and disease pressures.

Since genetic variation exists within the different traits that measure heat stress, it is possible to improve the animal’s ability to tolerate high stress situations. However, the quickest results will be obtained by crossing exotic breeds with either Bos indicus (Barendse 2017) or Sanga breeds. The most important principle remains that selection should take place under conditions where the animals are able to produce.

Read more about epigenetics here.

Easy-care animals

In an ever-changing world, productivity can only be maintained or improved with a more holistic view of livestock performance. Breeding easy-care animals that calf unassisted every year, and raising the calf to a marketable weight, should be a priority. Selecting for easy-care traits should result in more robust animals that are less dependent on human caretakers. An easy-care animal is thus a product of selection for fertility, production as well as welfare traits. Heritability of fertility traits are generally low; however, some fertility traits are moderately heritable.

Various traits are connected to animal fertility, but for an easy-care animal, aspects such as age at first calving, ease of calving, calving interval and/or days to calving are relatively easy to measure. Thus, if proper records are kept, these traits can be improved (Koots et al., 1994). Birthweight is also correlated with these traits. Thus, selecting for a lower birthweight increases calving ease, decreases calving interval, etc. (Bennet et al., 2021).

Several traits associated with animal welfare have been shown to be heritable, and to list them all is outside of the scope of this article; however, genetic variation exists for resistance to various diseases, as well as internal and external parasites. It is therefore possible, if data is available, to reduce disease prevalence and breakdown severity through selectively breeding for enhanced host resistance to the disease and/or parasite (Raphaka et al., 2018).

Influence of the consumer

In recent times, the consumer has become more attuned to not just where their food comes from, but also how their food was treated (Stampa et al., 2020). This does not just include the general welfare of the animals, but also relates to usage of substances such as antibiotics and hormones.

In general, it has become routine for consumers to voice their opinions regarding animal management, rearing practices, and the possible environmental impact of livestock farming, among many others. Selection for an easy-care animal would indirectly also affect many of the welfare traits that concern the consumer.

The consumer of today has also become more educated on what constitutes good meat quality and have started to demand it in the products they choose to purchase. Many of the welfare traits are also indirectly correlated to meat quality; however, advances would be marginal and slow without direct selection for improved meat quality.

Meat and carcass traits are influenced by diet and feeding practices, pre- and post-slaughter management, and meat processing and storage methods (Grigolette et al., 2020). However, enough variation exists in these traits that genetic selection can be used as a complementary approach. The advantage of this is that any improvements in the traits would be permanent and cumulative.

Unfortunately, in South Africa there is a lack of meat quality data, especially meat tenderness and other traits that directly influence meat quality. However, traits such as longissimus dorsal muscle area, backfat thickness and marbling can be measured utilising real-time ultrasound.

All these traits have shown to have moderate to high heritability (0,16 to 0,33) (Grigolette et al., 2020) and therefore can be improved through selective breeding.

In conclusion

Genetic improvement is a cost-effective way to overcome modern challenges, especially since it can lead to permanent and cumulative changes in livestock production. However, data that implies accurate measurements on a wide variety of economically important traits, proper record-keeping and sire selection is required for maximum efficiency in both the stud and commercial industries.

Breeding climate adapted, easy-care and efficient animals that produce a fast-growing calf every year, and that has good meat quality, appear to not only be a viable strategy for the future, but one both the commercial and stud industries should seriously consider. – Errol Cason, Department of Animal Science, University of the Free State

For more information or a list of references, send an email to Errol Cason at CasonED@ufs.ac.za.