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Take the heat out of production

Heat Map

It seems timely writing a blog about heat stress exactly one week from the summer solstice. But with the current daily temperature at 13 degrees and parts of the UK having just experienced two months’ worth of rain in two days, it may have been more apt in February, when we had record highs of 20.6 degrees Celsius in Wales!

For a mature lactating cow, the level at which they begin to experience heat stress is at around 21 degrees Celsius and can be even lower in humid environments. With the relative humidity in the UK frequently above 80 percent, a temperature of 28 degrees Celsius would bring about the risk of severe heat stress, which will cause depressed feed intakes, reduced production, fertility challenges and a heightened risk of mastitis.

There are two main ways a cow maintains its own thermal balance in a heat stress situation. First, they increase their own heat dispersion through panting, drooling and increasing subcutaneous blood flow; efforts that cause repartitioning of energy away from production by as much as 20 percent at 35 degrees Celsius. Second, they will try and limit their own metabolic heat production. As the majority of their heat production is coming from rumen fermentations, they will reduce their dry matter intake by 10-30 percent.

The reduction in nutrient intake and lift in energy demand has an immediate effect on milk production. In these instances, we would advise an increase in the concentrate-to-forage-ratio within the diet, so as to try and maintain the required nutrient intake. Ideally, we need to condense the energy and protein sources within the diet using bypass fats and Optigen®. Optigen is a highly concentrated, controlled release protein source, which allows the same crude protein content to be produced in up to 1 kilogram less dry matter. The use of Yea-Sacc® live yeast has also been proven to reduce the risk of acidosis and butterfat depression by maintaining a consistently higher rumen pH, enabling better digestion and improving feed efficiency.

Finally, when the sun is out, and the mercury is rising, we all like to have a drink! Dairy cows are no different. Water makes up about 85 percent of milk content, so as the temperature goes up, so does their water requirement. In fact, water requirement can double in a heat stress situation, which means each cow could be looking for more than 140 litres of water every day. For housed cattle, we need 10 centimetres of linear water trough space per animal. Flow rates are also important, as the total daily supply should be available within a six-hour period. Trough volume helps with this, but attention to cleanliness of water is essential in maximising uptake.

For further advise, or to arrange a free on-farm visit, please call 01780 764512.



Chris Lord, InTouch UK Manager


Tel: 07787 571526