Heat stress warning for cows

RECENT HIGH temperatures could be causing heat stress in dairy cows, resulting in reduced feed intakes, increased water consumption and lower yields.

Heat stress can start at 20C and an increase in temperature to 25C is enough to reduce dry matter intakes by 0.5kg/cow and reduce yield by two litres a day, says Andrew Pine of Premier Nutrition.

When dissipating heat cows increase sweating. “Increased sweating means cows lose more mineral salts, such as sodium and potassium and these will need replacing. Cows should be provided with adequate minerals to replenish levels reduced by higher levels of sweating,” he adds.

And its not just direct sunlight which increases heat stress, poorly ventilated buildings and high humidity can also play a part, as can walking to the parlour. “Walking half a mile can raise a cow’s body temperature by 2C for up to 10 hours.”

Where heat stress is suspected Dr Pine advises improving ventilation wherever cows congregate, installing sprinkler or misting systems in collecting yards and ensuring drinking water is clean, plentiful and accessible to the whole herd.