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Heat detection – is she or isn’t she?

Heat detection – is she or isn’t she?

It is well documented that modern day high yielding cows express heat with a lower intensity and duration. The reduced intensity of heat expression and subtle expression of secondary signs of heat may lead to uncertainty over an animal’s heat status, particularly if the cow has returned at an irregular interval.

Studies have shown that around 10% of cows are served when they have high progesterone (not truly in heat). Interservice interval data may give a clue as to whether heat detection is accurate on farm; high percentages at 25-35 days and particularly at 1-17 day intervals generally warrants further investigation to rule out heat detection inaccuracy on farm.

Insemination of cows that are not in heat will inevitably reduce the apparent conception rate on farm. Inaccurate heat detection is not only associated with a waste of semen but can lead to pregnancy loss in around 17% of inseminated pregnant animals. Approximately 6% of cows show overt signs of heat despite being pregnant. A quick way to confirm that a cow is not in heat is to use a milk progesterone test, cow side progesterone tests are available that can be used on farm for around £3/cow. High progesterone indicates that the cow is not in heat.

For further advice, please contact the Oakhill Farm Vet Team on 01772 861300