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One of our southern monitor farms kindly shared what the impact of the recent heatwave had been on his farm.

Feed intakes were down 6kg of fresh TMR per cow per day across the milking herd and yields were down about 3 l/cow/day. With about 350 cows in milk and a summer milk price of 42 ppl this is a drop in milk sales income of £441/day – or about 9% of the total milk income. Feed rates, etc. will not have changed so this is all off the bottom line.

[my ‘back of envelope’ calculations suggest a fall in energy intake of about 30 MJ ME/day and a fall in energy committed to milk of about 15 MJ ME. This concurs with American research findings – the remainder (50%) is lost to supporting the increased inflammatory condition in the intestines]

The fall in intakes also affected the transition cows and they were seeing more RFM’s and the cows were not ‘starting up’ as well as they should.

They noticed more standing and huddling (see picture) – and it is noticeable how they are hugging the shade. They report more lameness and this may continue through the autumn due to excessive solar bruising.

All in all the total cost is probably about £1000/day to this herd.

They report that the maize is all harvested and they are looking forward to cooler, autumn weather!