AFTER a series of record-breaking heatwaves hit the UK – and another forecast for the Bank Holiday weekend – an agricultural expert is warning about the potentially fatal impact of heat stress on livestock and outlined steps farmers can take to reduce the risk. 

Mercury levels continue to climb year after year, with June 2019 officially named the hottest June in recorded history. 

July saw temperatures soar even further, breaking global temperature records. 

Despite a wet and windy start to August, the Met Office is predicting temperatures will start to climb again this weekend, with hot weather expected to remain until September.

As heatwaves become more commonplace, Sarah Verity, of Farmers and Mercantile Insurance Brokers (FMIB), urged farms – particularly mixed farms – to not overlook the effect of rising temperatures on livestock and to take these precautionary measures against heat stress.  

Beef Cattle

Cows out to pasture are not usually as susceptible to heat stress as those kept in sheds.

However, working them during periods of extreme heat should be avoided; try to stick to early mornings. Evenings should also be avoided as it can take cows six hours to bring their core body temperatures back down to normal after being exposed to extreme heat.

Cattle naturally produce a lot of heat whilst they’re eating, and this peaks around four hours after feeding. Therefore, cattle kept in sheds need to be fed earlier than usual to avoid their body temperatures peaking in the middle of the day.

Dairy Cattle

Dairy cattle can start to experience mild heat stress from around 20C.

Increased ventilation, fans, shade and sprinklers can all help with reducing body temperatures. These should be used in holding pens and milking parlours, as cows are under increased stress in these areas.

Access to water should be a given but intake is likely to double under heat stress. Make sure calves in huts or cows separated for rest have additional water, as these animals are more susceptible to heat stress.

An increase in moisture caused by excessive sweating can also lead to mastitis.


Pigs are much more sensitive to heat than other animals because they lack the ability to sweat.

Signs of stress in pigs include open-mouth breathing, vocalisation, blotchy skin, stiffness, muscle tremors and reluctance to move. If pigs begin to demonstrate these symptoms, allow them to rest, keep them cool with fans and have access to plenty of water.

It can be helpful to sprinkle cool water onto the pig.  Avoid pouring large amounts of cold water onto the pig, as this could cause shock.

Pigs housed outside need plenty of shade.


Sheep tend to be less susceptible to heat stress than other livestock. Wool protects sheep from extreme heat, as well as extreme cold.

Make sure sheep have been sheared and pay close attention for issues caused by flies.

During periods of extended heat and humidity, it may be necessary to provide extra water.


Poultry are highly susceptible to heat stress, and the first sign of this in the bird is panting.

To prevent overheating, keep sheds well ventilated, look to decrease the number of birds per square metre and keep water sources fresh and cool.

Birds produce heat whilst digesting food so look to feed birds during the cooler parts of the day. With broilers and turkeys remove feed from the birds around six hours before peak temperatures and reintroduce once it starts to cool.

Working Dogs

Don’t forget about your working dogs during extreme heat.

Avoid working them during the peak of the day. Keep dogs in well ventilated shade and with regular access to water. A shallow paddling pool is a fast way for a dog to cool down their body temperature.

Avoid taking dogs with you in the tractor or pick up whilst temperatures are high.

If animals are displaying signs of heat stress, farmers are advised to seek veterinary help immediately.  Farmers who are interested in protecting their livestock against the effects of heat stress can speak to their insurance broker to discuss the options available.