Understanding the importance of Heat Detection

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Signs dairy cows are on heat

Understanding the importance of Heat Detection


Pregnancy drives economics for dairy farmers, so having a heat detection plan is critical. As a specialist in reproductive efficiency, Dr Ky Pohler, Assistant Professor Texas A&M University is interested in helping farmers increase fertility by decreasing pregnancy loss.

The research has shown that in dairy cattle, following initial conception (on average 80%), up to 30% of the pregnancies are lost in the early embryonic period (P1) (first pregnancy exam). There is then a further 12% loss as late embryonic mortality.

These findings are also supported by a large NZ study led by AgResearch and published in the September 2016 DairyNZ Technical Series – “Research finds most pregnancy losses occur in first week”. This work states that the pregnancy rate 70 days after first insemination was 55%, with a fertilisation rate of 86% of eggs, when cows are inseminated at the correct time.

The big question Dr Pohler and his team asked was why do cattle, which are positive in P1, go on to undergo pregnancy loss?

Having a heat detection plan is critical

One clue they have uncovered is the significance of the relationship between the intensity of estrous at the time of AI and pregnancy holding rate. Cows showing strong estrus intensity at the time of AI may have an improved pregnancy holding rate. With this being so important, how can farmers ensure they are mating at the correct time of the estrous cycle?

This is where having a heat detection plan is critical and there are many elements to consider, including the correct use of Heat Detection aids.

Dr. Pohler explains that they used Estrotect patches in our research. “They have been invaluable because the farm staff and research technicians can use the patch score as a clear indication of estrus intensity.  We have scored patches on over 10,000 animals in our data set.”

Estrotect clearly shows if the cow is ready to breed

In 2019, Estrotect introduced an additional feature which clearly shows whether the animal is ready to breed or not. Patches are scored from one to four, with scores three and four indicating strong estrus intensity.

CRV Sales and Marketing Manager Jon Lee says Estrotect has been a popular heat detection choice for dairy farmers for many years.

“We’re really pleased to see the latest research results confirming the relationship between a cow’s estrous intensity and her pregnancy holding rate.  With Estrotect, we’re confident we are providing our farming customers with a reliable tool to help them successfully detect premating heats. Farmers have a lot riding on their AI so we want to ensure they are putting cows up at the right time to minimise the risk of pregnancy loss.”

Find our more about improving Heat Detection with Estrotect here


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