Heat stress is a major source of production losses in cattle in the Northern Cape. Fluctuating cold and hot temperatures, thermal radiation, humidity and wind speed can cause stress and suboptimal performance and lower productivity in animals.
According to an article by Farmer’s Weekly the risk of heat stress should be assessed by means of the temperature-humidity index in order to take preventative measures against the adverse impacts of heat stress and extreme weather conditions, such as: anoestrus-induced abortion, calves with lower birthweights and growth rates, poor quality colostrum and delayed puberty in heifers.
The temperature-humidity indices of the South African Weather Service can be applied to assess the impact of extreme weather conditions on livestock. “The temperature-humidity index (THI), for beef cattle particularly, is calculated as follows: THI = 0,8 + RH*(Ta – 14,4) + 46,4 where RH indicates relative humidity and Ta indicates dry-bulb temperature.”
This tool can be used to assess risks and prevent effects on animals, which can be beneficial to Northern Cape farmers who often suffer losses due to the negative effects of extreme climates in the province. The extent of heat stress is also expected to become more severe because of geographical location, climate change and the extended drought in the area.
More hardy indigenous breeds with small to medium body sizes are recommended to livestock producers in the area as a long-term solution to the adverse effects of heat stress as they are more adapted to the climatic conditions found in the Northern Cape. “Breed, frame size and production level also affect animals’ biological responses to stressors.”
Smaller breeds also have a faster metabolic rate which enables them to cope in conditions that suffer regular draughts. Farmers should therefore bear in mind that it is more economic to select breeds that are adapted to climate conditions, than to adapt the environment to the breed.
Read more on Farmer’s Weekly.