Experts share top tips on how to protect cattle and sheep from heat stress

The experts have identified the main signs of heat stress in livestock, which are, among others, refusal to lie down; huddling or bunching, especially around water troughs or fresh, cool air breezes or near the top of sheds; body splashing – attempting to wet coat by splashing head in water trough; increased drinking and/or increased respiration rate; as well as high rectal temperature over 39°C in cattle and 41°C in sheep.

Open-mouth breathing, head extended, tongue protruding, profuse salivation and front legs held wide to increase lung volume are also signs of advanced heat stress.

If nothing is done to relieve the situation and their body temperature remains high, the animal could collapse and die, AHDB warns.

High temperatures can also affect feed intakes, growth rates, ovulation, conception rates and bull/ram fertility.

AHDB experts have created a list of top tips for preventing heat stress in cattle and sheep.

Managing cattle in hot weather

• Make sure all cattle have access to a good supply of clean drinking water and keep water out of direct sunlight. Water intakes will increase by up to 10–20% in hot weather
• Avoid unnecessary handling of cattle. Handle cattle quietly and calmly in the early morning and not in the heat of the day. Cattle need time to recover from high daytime temperature, so avoid handling in the evening as well
• Give cows the option to go inside if they find that more comfortable
• Reduce walking distance to the parlour
• Reduce time spent in holding areas and avoid keeping animals too tightly stocked in collecting areas or pens
• Consider feeding in the late afternoon rather than the morning. This will allow the heat from rumen fermentation, which peaks four to six hours after feeding, to be dissipated during the cooler evening/night-time
• Provide shade where possible. Offer housing as shade – covering or painting over translucent roof sheets in a shed can dramatically reduce the temperature. Trees can provide shade, but cows camping under trees is a high risk for Strep uberis
• High temperatures can also affect fertility. Be aware of the potential for reduced intensity of expression of heat and longer oestrus periods in breeding females
• Take steps to control flies, as these can spread disease and cause cattle to congregate
• Cool cattle by using a water sprinkler system to wet their coats after milking
• Air movement – ideally generate at least 1.5–2 m/s air movement (breeze) for skin cooling and to evaporative heat loss. Place fans over beds to encourage lying times (rest), set at the right intervals and angled to blow down onto the cows. Helicopter-style rotor fans can do this too. In UK conditions, the stack effect is still the best way to drive air exchange and remove humidity. This means farmers should focus on fans for air movement at cow level within the shed, as opposed to fans for air exchange. This is quite different from artificial ventilation in calf houses, where the aim is to use mechanical means for air exchange, while avoiding excessive draughts at calf level
• Pay special attention to sick cows. They are likely to benefit from rapid and regular pumping with a sufficient volume of oral fluids and electrolytes.

Managing sheep in hot weather

• Provide grazing stock with access to fields that have sufficient shade from hedges or trees and be alert for fly problems. If necessary, consider housing animals
• Move, gather, handle or transport animals in the cooler conditions of the early morning or late evening wherever possible
• Give special attention to lambs because they are more susceptible to heat stress than adult sheep
• Consider providing extra forage during the cooler times to help compensate for reduced feeding activity in the heat
• Make sure all sheep have access to a good supply of clean drinking water
• If housing, ensure buildings are adequately ventilated and increase space allowances by reducing stocking densities if possible. There should be 1m² of floor space per ewe and 0.6–0.7m² per lamb (25–35 kg)
• Maintain good drainage and ventilation in areas of accommodation prone to wetting to avoid the additional heat stress caused by high humidity.

Managing prolonged dry conditions

As it comes to grassland management, AHDB recommends to farmers to avoid overgrazing and protect regrowths by not grazing below the 1,500 kg DM/ha (4 cm) residuals. 

Farmers should also consider having a sacrifice field to avoid overgrazing paddocks, maintain rotation length at 24–28 days if grass growth has slowed down and be careful of carrying fields with high grass cover, as these might go backwards. 

AHDB experts added: “Do not apply N fertiliser if no rain is in the forecast, as the plants will have little ability to utilise this into growth in dry conditions, and it risks livestock ingesting fertiliser, which is toxic.” 

Farmers have been also encouraged to “make a plan B” to fill a possible deficit gap.

Water 

Water requirements for milking cows is 120–140 litres per day. A 70 kg ewe at peak lactation requires more than 7 litres per day and a lactating suckler cow will drink 40–70 litres, AHDB explained. 

Trough capacity and pipe size must be correct to supply water rapidly. Farmers need to provide enough space so all those that want to drink at any one time can do so. 

“Consider placing extra troughs in the fields or near the parlour if it does not restrict cow flow. This takes the pressure off the trough in the field. 

“Check regularly – algal growth and contamination will reduce water consumption,” the AHDB experts concluded. 

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