Beating heat stress in cows

Keeping cows cool during extended periods of summer heat and sunshine can be challenging. Angus Little, NWF Sales Specialist looks at beating heat stress.

Fresh calvers and high yielding cows are particularly susceptible to metabolic disturbances. Already under the metabolic stress caused by the demands of lactation, a drop in dry matter intake which is often associated with hot weather only exacerbates the problem.

Heat stress impacts rumen pH in two ways: firstly, DMI is decreased which results in decreased saliva production and therefore reduced rumen pH as it is a rumen buffer. Secondly, heat stress also brings on slobbering, which means less saliva reaching the rumen and consequently a reduction in rumen pH also.

Heat stress can occur in housed animals as well as grazing animals. Signs of indoor heat stress include cows sticking their nose out doors and windows seeking fresh air and reduced intakes. Cows will be more likely to eat in areas where there is more fresh air so that they can cool down at the same time.  When given the option between eating inside or outside they will nearly always choose to eat outside.

To combat heat stress, fresh water should always be available. Water intake helps cows cope with heat stress; bear in mind that, while cows can drink at 15 litres per minute, they only drink for about 30 minutes per day, most of it within 60 minutes after milking, so adequate trough numbers, capacity and flow rate are critical.

If cows are showing signs of heat stress indoors you need to bring more fresh and dry air from outside using fans. When choosing where to site fans, priority starts with the close-up transition cow housing, followed by the holding area immediately prior to milking as cattle packed together are at prime risk. Then make sure the cow beds are covered.

Inevitably, high temperatures depress appetites, leading to increased sorting. To maximise intakes, ensure feed is fresh by feeding out regularly.

Do not reduce the overall volume fed as the energy density will drop and therefore performance.

Instead, look to boost DMI through the addition of molasses and water, and targeted use of supplements/additives such as yeasts, and NWF’s Healthy Rumen Pak.

All NWF diets include Cell Shield®, an anti-oxidant designed to optimise production and cattle health. It supports and regenerates vitamin E within the cow’s system, helping improve immune response, which can help reduce somatic cell counts as well as the risk and severity of mastitis and other infections.

For more advice on cattle management and Cow Signals, plus information on the NWF range of summer feeds and supplements, call 0800 756 2787.