Managing cattle and sheep in hot weather

In dry and warm conditions, it’s important that farmers consider the effect heat can have on their livestock. Read our top tips for preventing heat stress in cattle and sheep.

• Refusal to lie down – perhaps 21–22 minutes less for every 1°C increase in ambient temperature above 21°C. This increases the risk of claw horn lesions within the subsequent 4–8 weeks. These may include heel ulcers, which some trimmers call sole fractures
• Huddling/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
• Increased respiration rate – especially serious when accompanied by deep flank movements
• 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, which is a sign of advanced heat stress

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

High temperatures will also affect:

• Feed intakes
• Growth rates
• Ovulation
• Conception rates
• Bull/ram fertility

• 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 day time 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 4–6 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 to 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 sufficient volume of oral fluids and electrolyte.

• 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 1 m² of floor space per ewe and 0.6–0.7 m² 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

• Don’t overgraze and protect regrowths by not grazing below the 1,500 kg DM/ha (4 cm) residuals
• Consider having a sacrifice field to avoid overgrazing paddocks
• Maintain rotation length at 24–28 days if grass growth has slowed down
• Be careful of carrying fields with high grass cover as these might go backwards
• Don’t 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

• Bales are a good option in a dry period as they can be opened almost immediately after baling. Ideally, clamp silage needs to be left for eight weeks after harvesting to reduce the risk of aerobic deterioration. If you require forage soon, leave clamps closed for four weeks before feeding
• Fill the forage shortage as economically as possible while protecting and monitoring winter forage stocks
• Dig deeper to see how certain feed options stack up in terms of relative cost per unit of energy and protein
• Reduce the cost of bought-in feeds and forage by buying in bulk and locating local sources, where possible, to keep transport costs down
• Cull empty cows/ewes or poor doers to help reduce the stocking rate, if you have the opportunity to do so
• Monitor body condition score for dairy cows, beef cattle and ewes
• Autumn calvers should consider opportunities of drying off herds earlier to reduce demand
• Plan ahead for winter straw requirements and assess alternative bedding options

• 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
• Trough capacity and pipe size must be correct to supply water rapidly. 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