Heat Detection Strategies for Dairy Cattle

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When the time comes to examine a herd's dairy reproductive management program, producers often want to discuss low conception rates. In most cases, however, inadequate heat detection is a much greater reproductive problem.

Heat detection is the first step to getting an animal bred. According to DHIA records, producers in Georgia are only seeing a third of their heats.

Missed heats are one of several factors that contribute to long calving intervals. By increasing the number of heats observed, it is possible to shorten the interval between calves.

At the same time, both breeding’s per conception and heat detection efficiency increase when milk production increases. This indicates that producers can have greater milk yield along with good reproductive performance.

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Effective heat detection encourages a producer to take advantage of the superior genetics available through artificial insemination (AI). Daughters of AI bulls generally produce 1,200 pounds more milk per lactation than non-AI daughters.

More than 90 percent of cows should show heat by 50 days postpartum. Cows should cycle every 21 days at that time.

The most reliable sign a cow is in the heat is standing to be mounted by a herd mate. Each stand lasts only 4 to 6 seconds. Cows average about 1½ mounts per hour and are in heat 6-8 hours.

Therefore, cows are only in the heat a little more than a third of a day and only spend a total of 3 to 5 minutes actually standing to be mounted. It is easy to understand why cows must be observed for heat several times daily.

Also, producers should monitor secondary signs of heat. These include:

  • mounting other cows
  • clear mucous discharge
  • chin resting and rubbing
  • swollen red vulva, frequent urination
  • muddy flanks and ruffled tailhead
  • bawling, restlessness, sniffing behavior
  • decreased milk production and off feed

These indicators may signal that a cow is in heat, coming into heat or going out of the heat. However, base the decision to inseminate on standing heat, not on secondary signs of heat.

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