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We are suffering our first heatwave of the summer. The weather changed subtly last Friday with a change in wind direction and since then heat stress risk and THI scores have rocketed. All regions have recorded heat stress and all are suffering some milk yield losses with a clear trend from South to North and with coastal areas being cooler. Predicted losses have been as high as 3-4 l/cow/day over the weekend and averaging up to 1.5 litres (Hants) over the week. Remember that there is a lag of about 2 days between scores rising and milk yields dropping so we will see the impact from tomorrow onwards. The weekly weather forecast is for continued hot weather so heat load will accumulate and the cows will be suffering.

Provide as much shade, water and airflow as possible and make sure everything is working as it should! Support the rumen with careful feeding and using rumen supporting additives and buffers. Avoid over crowding especially in the collecting yard.