Keeping dairy cows cool this summer
Date published:
Historically, summer temperatures in Northern Ireland have not been considered a limiting factor in dairy production. Recent climatic trends suggest even moderate increases in temperature and humidity can negatively impact cow health and productivity, at temperatures above 20°C cows can begin to exhibit signs of heat stress.
Stephanie Reid, College of Agriculture, Food and Rural Enterprise (CAFRE), Dairying Adviser, outlines the signs and symptoms of heat stress and discusses practical solutions to keep cows comfortable.
Heat stress occurs when the cow’s ability to dissipate body heat is overwhelmed by a combination of two environmental factors - high temperatures and humidity. Cows need to maintain a constant body temperature of around 38.8°C +/- 0.5°C.
Stephanie outlines that: “Cows affected by heat stress will often appear lethargic, stand with bowed heads, display increased salivation, and have an increased respiration rate. When cows are stressed, they tend to move closer together into tight groups exacerbating the problem. They also spend more time standing rather than lying down. These behaviours increase the risk of lameness.”
Other effects of increased temperatures result in reduced feed intake, milk yield and conception rates, which are extremely costly for any farm business.
One key aspect of ensuring cow welfare during high temperatures is ensuring ample access to cool fresh water with a minimum trough space of 10cm per cow recommended.
At least 10% of cows should be able to drink at any one time. Consider positioning water troughs around areas such as the parlour exit as cows tend to drink up to 60% of their water intake after milking. Stephanie says that: “A cow producing 35 litres of milk per day, on a total mixed ration can require up to 145 litres of water when temperatures are over 20°C.”
Providing access to natural or artificial shade can help reduce the occurrence of heat stress. If on a grazing system, ideally bring cows into the house during the day from midday to provide shade and allocate a higher allowance of pasture for the evening feed. In the situation of housed cows, effective ventilation can improve air flow and cooling ability by using fans, vents and open sided walls.
Stephanie advises: “Consider some simple practical options such as removing wooden boarding around the building to help increase air flow and ventilation.”
Feed management can be altered to mitigate the impact of heat stress. Some options to maintain dry matter intakes include timing of feeding – offer more feed during cooler parts of the day, early morning or late evening and ensure feed is pushed up regularly to maintain intakes. Manage the clamp well to maintain feed quality and avoid secondary fermentation. Diet adjustments, for example, increase the energy density of a ration, while maintaining fibre levels so as not to cause rumen upsets.
Stephanie recommends: “Avoiding unnecessary handling of cows during peak temperatures. Group cows based on production level to manage feeding and mitigate heat stress risks. Keeping an eye on performance data such as milk composition as heat stress can be found to depress milk fat before a drop in yield is seen.”
Stephanie concludes that: “Prolonged exposure to warm conditions can significantly impact dairy cow welfare and productivity. Implementing proactive environmental and herd management strategies are essential to mitigate effects of heat stress and maintain herd performance this summer.”
If you would like to discuss managing heat stress within your herd, please contact your local CAFRE Dairying Development Adviser.
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