Underfeeding proves costly for dairy cow fertility results

SIX out of ten inadequately fed cows failed to go in calf to the first service in a Teagasc Moorepark trial which showed that infertility in dairy cows is a continuing major drain on high yielding herds.

The Moorepark research showed how underfeeding in the breeding season can reduce the rate of pregnancy to the first service by up to one-third. Where the supply of grass was adequate, the conception rate increased by 50%.

George Ramsbottom, Teagasc Specialist, said the annual culling rate in many high yielding dairy farms averages 22%, and is one of the biggest cost burdens.

“The single biggest reason for culling is infertility. The costs are substantial. Not only are replacement costs increased, but average herd yields are cut because fewer cows are surviving to produce mature yields”, he said. “The Teagasc target is a replacement rate of 18% rather than the 22% I’m seeing on client farms. This means that cows would produce for an average of 5.5 lactations instead of the 4.5 lactations we’re seeing at the moment. This is equivalent to a milk price increase of about 1.5 cent per litre”.

In the Moorepark trial, during a season of adequate grass, there was practically no difference between herds fed 5 kg per cow per day of concentrates and those on grass only.

However, when grass was inadequate the outcome was different. Cows on grass had a submission rate of only 91% in the first three weeks after turning out, and conception rates of 41% to the first service and 68% to the second service, and an empty rate of 18%. The cows fed 4 kg per day of concentrates, on the same pasture, had a submission rate of 95%, 64% conception to first service and 86% to the second service, and an empty rate of 9%.