Long- and short-term climatic patterns influence all livestock types: poultry, pigs, sheep, goats, dairy and beef cattle and others. Extreme environmental conditions, such as cold and hot conditions due to air temperature, thermal radiation, humidity and wind speed, cause stress and suboptimal animal performance, which lowers productivity. With beef cattle in the Northern Cape and North West in particular, but also in parts of KwaZulu-Natal, heat stress is known to be a major source of production losses.
THE TEMPERATURE-HUMIDITY INDEX
Globally, the level of heat stress is measured with different indices. In South Africa, the temperature-humidity indices of the South African Weather Services (SAWS) for different species of livestock are the broadly applicable formulas used to assess the impact of extreme weather on livestock. The index is a measure of apparent temperature, caused by the combined effects of air temperature and relative humidity on the subjective perception of heat and humid weather. Wind speed can be an aggravating factor. These handy tools can be used for risk management of heat stress and may prevent adverse effects.
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.
Although there are several categorisations of heat stress indices, SAWS has categorised the livestock weather safety index as ‘normal’ under 74, ‘alert’ between 74 and 79, ‘dangerous’ between 79 and 84, and ‘emergency’ when above 84 (see map).
Esta historia es de la edición December 11, 2020 de Farmer's Weekly.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor ? Conectar
Esta historia es de la edición December 11, 2020 de Farmer's Weekly.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor? Conectar
New farmers' seedling pitfalls
Inexperienced farmers may be tempted to grow seedlings from seed themselves, but they have much to gain by trusting a seedling grower at a nursery to perform this task for them instead
South African avocado production: a success story
Avocado production in South Africa has expanded markedly since the industry's humble beginnings over 80 years ago. From a small grove planted in 1938 in what was then Nelspruit, the industry has blossomed to seven million trees planted on 20 000ha. Dr Guy Witney, project manager at Great Brak Avos, spoke to Annelie Coleman about the country's avocado production.
Unlocking value through livestock exports
Exporting livestock might sound like a daunting business that's better left for big companies, but Gerrie Ferreira, who farms near Oudtshoorn in the Western Cape, has been doing it successfully for almost 30 years, sometimes in partnership with other breeders. He spoke to Glenneis Kriel about the huge potential this market holds, and offers some advice for farmers who are contemplating going this route.
An agribusiness's dedication to community upliftment
For agribusiness NWK, located in Lichtenburg, North West, corporate social investment is an important part of creating a positive influence alongside financial returns. Johan Bezuidenhout, NWK’s group manager of corporate marketing and communication, spoke to Annelie Coleman about why the company chooses to invest millions of rands in the area it operates in every year.
Empowering dreams, transforming lives
Since its launch in 2013, the Agri's Got Talent competition has revolutionised the lives of many farmworkers by unlocking their hidden talents and fostering a culture of empowerment. Glenneis Kriel spoke to various finalists about how the contest has changed their lives.
Foreign investment: agriculture maintains its appeal
South Africa remains a popular destination for foreign investors, despite an often negative outlook from its citizens. It is a gateway to Africa, and with its counterseasonal production to the Northern Hemisphere and favourable weather, local agriculture is especially well placed to attract foreign interest, bringing with it hope for rural communities
The real value and message of COP29 for SA agriculture
While the 2024 Conference of the Parties may have disappointed those who hoped for real progress, it's more important for South African agriculture to highlight its role in carbon mitigation
Improving efficiencies in feed and grain milling
Bühler, a Swiss-based company that provides solutions and equipment for various industries, including food and animal feed processing, has pledged that by 2025, it will deliver scalable solutions that will reduce energy, waste and water by 50% in the value chains of its customers.
Tips for better olive production
At an SA Olive Association field day in November, industry experts shared ways to improve olive production efficiencies, from soil preparation to harvesting.
More effort needed to protect vulnerable cheetah
On International Cheetah Day, commemorated every year on 4 December, emphasis was placed on the vulnerability of the species.
