Mitigating the risk of heat stress in cows

Heat stress in cows occurs when they are producing more heat than they are able to get rid of through sweating, respiration or air regulation (such as a breeze or wind, or by fans indoors).

An overabundance of heat in cows can lead to higher levels of stress, which can affect milk production, fertility, increase the risk of other diseases such as lameness, and impair immune function. Cows experiencing heat stress will exhibit behaviour such as seeking shade, loss of appetite, crowding together for increased shade, panting, drooling, and standing in water or next to troughs.

Heat stress in dairy cattle is probably the most overlooked seasonal problem here in New Zealand. Production drops rapidly as the heat increases, and most farmers simply accept this as a normal seasonal issue that they are powerless to address. The truth is, there are a number of nutritional strategies that can be used in order to mitigate the effects of heat stress.

When a cow is suffering from heat stress, one of the major issues they face is a reduced feed intake. With reduced feed intake and an increase in drooling, availability of saliva is reduced, which can disrupt the pH of the rumen and lead to acidosis. A healthy rumen is needed for milk yield as well as animal health.

Much scientific work has been done around the study of heat stress and how to mitigate the issues it creates. It is therefore important that ruminant animals during periods of high humidity are provided with sufficient nutrients in order to counteract heat stress and maintain strong immunity.

Feed additives shown to work well against heat stress are those that promote good rumen pH stability, and include additives such as rumen buffers and live yeast. Other additives that underpin healthy rumen function and immunity are trace minerals such as cobalt, selenium, zinc and chromium. Seaweed extract has also been well studied to show excellent results.

By providing your herd with an easily digestible, nutrient-packed animal tonic that can be blended easily into their feed or added into their water, you ensure that they have the correct balance in place to mitigate the effects of this summer heat stress.

Chris Balemi is managing director of Agvance Nutrition Ltd