Estimated reading time: 7 minutes
Climate change poses a serious threat to livestock production in South Africa, with heat stress emerging as one of the most pressing challenges. As temperatures rise and extreme weather events become more frequent, the resilience of livestock systems will be tested like never before.
According to Prof Michiel Scholtz, a specialist researcher at the Agricultural Research Council (ARC)-Animal Production in Irene, South Africa is expected to be among the countries most severely affected by climate change. The region is likely to experience more frequent and intense droughts, severe flooding, prolonged heatwaves, and higher temperatures.
In this context, indigenous livestock breeds, which are already well adapted to harsh environmental conditions, may hold the key to building a more climate-resilient agricultural sector.
Temperature and breeding seasons
Average temperatures are projected to rise by 1,5 to 2°C, with regional variations ranging from 0,5°C along the coast to as much as 3°C in eastern Namibia and western Botswana. In the case of ruminants, these temperature increases can negatively affect productivity (slower growth rates, reduced milk yields, impaired reproductive performance, and increased vulnerability to infectious diseases).
The implications for traditional breeding seasons are complex and difficult to predict. According to meteorological statistics, the coldest months have been June and July, but recent data suggests a shift towards July and August. If similar changes occur in peak rainfall periods, breeding seasons may need to be adjusted accordingly.
To maximise the use of natural grazing – the most cost-effective feed source – breeding seasons should align with periods when animals’ nutritional needs are at their peak. Given that grass production varies significantly across South Africa, and that climate change may further alter both the quantity and quality of grazing, breeding periods must be tailored to specific environments.
Sustainable livestock farming will require working in harmony with nature. This includes strict selection for adaptability, particularly identifying females that calve early in the season. Bulls must also be resilient and capable of performing under changing climate conditions.
Producers must prepare for a future marked by gradually rising temperatures and declining rainfall. These changes are likely to reduce pasture quality, both in terms of edible biomass and nutritional value. An increase in tickborne diseases is also anticipated, potentially leading to higher mortality rates.
Read more here about indigenous veld goats.
Heat adaptability
Heat stress is emerging as one of the most significant challenges in cattle production, says Frans Jordaan, senior researcher and a colleague of Prof Scholtz. Cattle begin to experience heat stress when temperatures exceed 28°C, and the situation is exacerbated by high humidity, which hampers animals’ ability to cool down and regulate their body temperature. Additional factors such as digestive heat generated in the rumen, direct sunlight, and hot winds further intensify heat stress.
In South Africa, the primary breeding season coincides with the peak of summer – often the hottest time of the year – placing additional strain on cattle. Research conducted by the ARC on an adapted Bonsmara herd revealed that heat stress had the most detrimental effect on herd productivity. Both bulls and cows suffer reproductive setbacks under these conditions.
Prof Scholtz highlights that one of the most common consequences of heat stress in bulls is a decline in semen quality. Once semen is compromised by heat, it can take up to eight weeks for a bull’s semen quality to return to normal. Even a single day of heat stress can significantly impair a bull’s fertility by reducing both the quantity and motility of sperm cells. This issue is exacerbated by the proximity of the testicles to the ground, where radiant heat further elevates temperatures.
Cows and heat stress
Cows’ reproductive capacity is negatively affected by extremely high temperatures, which can alter and weaken the cellular functions of various tissues within the reproductive system. Heat stress also has several indirect effects, such as the redistribution of blood flow between organs, reduced feed intake, and the onset of respiratory alkalosis. The disruption of hormone dynamics during the cow’s heat cycle can lead to impaired ovum development. In the early stages of pregnancy, such stress can also impair embryo development and increase the likelihood of embryo loss.
During late pregnancy, heat stress can have lasting consequences on the performance of suckling calves. For instance, a trial conducted in Hartswater showed that temperatures reaching up to 42°C caused a 42% variation in calf weaning weights. The severe heat wave of 2015/16 further highlighted these effects: European-type cattle in the trial experienced up to a 17% reduction in average weight gain, while Sanga-type cattle showed a 9% decline. Heat stress can also diminish meat quality in certain cattle breeds, affecting both tenderness and colouration.
Influence on condition score
Because prolonged heat waves and droughts can significantly alter the composition and nutritional quality of grazing, it is crucial to prioritise nutrition alongside heat stress management. The breeding season typically follows a harsh winter, during which cows are often underweight. Only about 50% of cows with a body condition score (BCS) of 2 or lower at mating will conceive within a two-month breeding window.
Ideally, cows should have a BCS of around 3,5 at mating, and more importantly, their condition should be on an upward trajectory at that time.
From an economic standpoint, it is far more cost-effective to maintain a cow’s condition throughout challenging periods than to attempt rapid weight gain through supplemental feeding just before mating. The latter approach is not only expensive but often unsuccessful.
Indigenous livestock breeds
Indigenous livestock breeds offer a significant advantage due to natural selection over centuries, enabling them to thrive in the demanding conditions of the African climate. In the early stages of their development, these animals had to survive with minimal resources and in harsh, natural environments. Only the most resilient individuals survived, leading to hardy, well-adapted animals.
These indigenous cattle breeds are typically hardy and adaptable, with smaller frames. They often possess smooth hair coats that help limit tick infestations, and they exhibit natural resistance to internal and external parasites. Their skin pigmentation offers effective protection against sunburn, and they are known for their calm temperament, longevity, and ease of calving. They also tend to have long, wide, and deep carcasses, along with excellent walking ability.
According to Prof Scholtz, a climate-smart approach that emphasises livestock adaptability and sustained reproduction and production is essential. In this context, South Africa’s indigenous cattle breeds represent a vital legacy for food security. These breeds excel at being veld cattle, with inherent traits of hardiness and adaptability that have not been altered by modern breeding techniques.
Managing change
Jordaan says while breeders have limited control over environmental and climate conditions, they can still influence productivity through strategic management. Practices such as effective pasture management and the use of cultivated pastures can create a more favourable production environment. However, the most effective strategy remains selecting animals that are naturally suited to the specific environment.
Choosing adapted bulls from breeders within a producer’s own farming environment can significantly enhance herd adaptability and reduce the impact of heat stress. For livestock production to be sustainable and profitable, producers must supply high-quality animals that meet the demands of a competitive market. These demands often include minimum growth rates or weaning weights, especially when calves are destined for feedlots.
Prof Scholtz says that achieving long-term success also requires a focus on selecting efficient cows. This is determined by three key traits: the calf’s weaning weight, the cow’s nutritional requirements allowing her to rear the calf, and the length of the cow’s calving interval.
Crossbreeding and hybrid vigour
Crossbreeding systems can be effectively utilised to enhance cow efficiency (kg calf produced per large stock unit or LSU). Indigenous cattle breeds can play a crucial role in these systems. When crossbreeding is properly planned, significant improvements in cow efficiency have been observed – for example, Simmentaler x Afrikaner crosses showed a 15% increase, Angus x Nguni crosses improved by 21%, and F1 Afrikaner cows an up to a 49% increase, all without incurring additional costs.
Crossbreeding systems also offer other notable benefits. Between weaning and marketing crossbred calves added 26,6% more value to the meat produced and consumed 26,7% less feed than their purebred counterparts. These advantages make crossbreeding systems, especially those involving indigenous breeds, particularly valuable for communal and emerging producers. – Andries Gouws, Stockfarm
For more information, send an email to Prof Michiel Scholtz at gscholtz@arc.agric.za or Frans Jordaan at fransj@arc.agric.za
