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In Southern England we have had great weather over Easter. Our two Labradors where panting and keen to seek out any cool shade – so how were more productive dairy cows coping? Temperatures reported by our Heat Load Monitors over the long weekend are shown in the graph.

The temperatures inside a modern cow shed and outside in the shade were pretty similar. They dropped down to around 8 – 10’C each night then rose quickly until 9:00 to 11:00am before falling away in the afternoon and through the evening.

The temperatures in the full sun where more extreme with a higher peak each day up to 23’C to 26’C on different days. At these temperature high yielding cows, especially black coated animals, would quickly accumulate heat. Responses would be shade seeking, panting and increased water intake.

However, the fall in temperature overnight to below 10’C would allow accumulated heat to be shed so there would be no long-term effects  on productivity, health and fertility. Shade is so important for grazing cows but providing enough (6 sq m / cow) in intensive grazing systems with tight paddock management can be very challenging.

Dairy Cow Heat Stress