As summer gets into its stride, ForFarmers is urging dairy farmers to implement preventative measures against heat stress, which can significantly impact milk production and herd fertility.

Andrew Torrens, Ruminant Specialist at ForFarmers, highlights the ideal ambient temperature for dairy cows ranges between 5°C and 25°C, or lower if the humidity is higher.

He says: "We don't operate at our best when we're hot and bothered and the same applies to cows. Once temperatures exceed this range, cows begin to show signs of heat stress such as panting and drooling. These self-regulating behaviours reduce feed intake, impacting overall productivity.

"The effects on fertility can be seen in the form of reduced pregnancy rates," he adds. "It's vital producers start planning now to help their herds cope with rising temperatures."

To maintain high feed intakes during periods of hot weather, Andrew advises feeding fresh feed in the cooler hours of the day. He also recommends increasing dietary energy density and using high-quality, easy-to-digest feeds to reduce heat from fermentation while supporting intake and performance.

Additional recommendations include:

•             Shade and shelter: Grazing herds should have access to shaded areas, and farmers may consider bringing cows indoors during the hottest parts of the day.

•             Water access: Whether cows are housed or grazing, ensuring an adequate supply of clean, cool water is essential. A lactating cow can drink up to 140 litres of water per day. Water troughs should provide a flow rate of 20 litres per minute — the rate at which cows naturally drink.

•             Cleanliness and space: Troughs must be cleaned regularly to prevent bacterial growth and encourage intakes. There should be at least 10cm of drinking space per cow to avoid crowding and ensure consistent intakes.

•             Ventilation: Good airflow is crucial in housed systems. Open or protected ridge vents, additional air inlets, and the use of fans — particularly in high-traffic areas like the collecting yard — can greatly enhance ventilation and cow comfort.

•             Fertility: include products such as Lintec which are high in energy to increase the density of the diet to help reduce the negative energy balance due to reduced intakes.