Cow Thermonitor: Cows struggle over 25degC

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“Dairy cows are truly remarkable animals,” he says. “They perform at very high levels in some quite extreme conditions, resisting the bitterly cold winter temperatures encountered in countries like Canada and Siberia and the baking heat of the Middle East without any apparent complaint.

“If we look more carefully, however, then the impact on production can be seen. The thermoneutral zone for cattle – the temperature they feel most comfortable at – is thought to be five to 25 degrees centigrade.

“Due to the heat produced by milk production and rumen fermentation, they appear to tolerate temperatures as low as minus 37 degree centigrade without too much impairment.

“However, this metabolic heat production causes problems when temperatures rise above the thermoneutral zone, with sudden changes of a few degrees over 25 degrees celsius causing some major problems.

“Typically we see reduced dry matter intakes followed by changes to claw health and reduced fertility. It is believed that sudden changes in environmental temperature cause the most problems.

“Having some measure of this and relating it to production in the UK dairy cow will be extremely useful to add to the experiences reported in Israel, North America and other parts of the world.”