Keeping It Cool: Dealing With Extreme Temperatures

South Africa’s increasingly common heatwave conditions pose a major threat to the country’s farmed cattle, sheep and goats, which often feed and live outdoors. Lloyd Phillips spoke to a number of experts in the field about the negative effects of extremely high temperatures on livestock, and practical methods a farmer can use to mitigate these.

- Lloyd Phillips

The South African Weather Service’s website states that if the maximum temperature in a particular area is expected to meet or exceed 5°C above the average maximum temperature of “the hottest month” for that area, and these conditions persist for three days or more, a heatwave may be declared. This summer, South Africa has already had heatwave conditions declared in various parts.

Prof Michiel Scholtz, a specialist researcher in applied animal breeding at the Agricultural Research Council’s Animal Production division and associate professor in animal breeding at the University of the Free State, says ambient temperature has a particularly significant impact on the productivity of ruminants such as cattle, sheep and goats.

EVOLVED TO STAY COOL

Dr Jan du Preez, a veterinary specialist for public health, explains that ruminants are homeothermic, which means that their bodies work constantly to maintain the stable core body temperature required for optimal health and productivity. When the ambient temperature exceeds the maximum upper limit of the animal’s thermoneutral zone, its body undergoes various adjustments to try to compensate for the effects of the higher temperature and cool the animal down.

“For example, blood vessels in the skin will dilate to dissipate heat from the animal into the air; the animal’s rate of respiration will increase to exhale warm air and to inhale cooler air; and sweat glands in the skin will start secreting moisture to help the animal benefit from evaporative cooling,” says Du Preez.

FEEDING AND DRINKING