Heat Detection in Dairy Cattle

Why is it important?

Reproductive performance depends on accurate heat detection. Poor heat detection is one of the most common problems in dairy cows and it is thought that at least 50% of heats are missed. For every heat missed from 65 days post calving there is a loss of 21 days of production costing on average £5 per day i.e. £105! Accurate heat detection is also important in the timing of artificial insemination (AI) as poor timing will result in decreased conception rates.

What are the signs?

Standing to be mounted is the only conclusive sign that an animal is bulling. A cow may be on heat for as little as 2 hours and with 70% of activity occurring at night it is important that a good heat detection strategy is employed.

Secondary signs such as attempting to mount other cows, swelling/reddening of the vulva, mucus discharge, restlessness, bellowing, chin resting, trailing other cows or increased activity are an indication that the cow may be about to come bulling or have been bulling. Best conception rates will be achieved by serving 12 hours after onset of standing to be mounted.

What factors affect heat detection?

o Floor surface - cows will not stand to be mounted on a slippery floor o Lameness and other disease - lame and sick cows are far less likely to stand to be mounted o Stress/bullying, this is especially important in heifers. o Poor lighting o Poor cow identification - freeze brands or ear tags

What is the best heat detection strategy?

It should be the responsibility of one person and they should have a simple recording system. Cows should be observed for a minimum of 30 minutes 3-4 times a day (not at milking or when feeding). Observation should be done early in the morning and late in the evening as this is when most activity occurs. Recording heats before first service and keeping 21 and 42 day return lists will help to remind you which cows to pay particular attention to.

Cows should be served in the evening if they are seen bulling in the morning and the following morning if they are seen bulling at night.

What are other heat detection options?

o Tail paint - cows must be observed at least once a day and paint reapplied regularly o Tail mount detectors e.g. Estrotect & KaMars o Motion detectors such as collars or pedometers - 24 hour monitoring so timing of AI can be maximised o Vasectomised bulls o Synchronisation programs by vet

How can Carmarthen Vet Centre help you improve your heat detection?

If you are milk recording we can access your records on Interherd and assess your heat detection using graphs like the one below. We can discuss your current approach to heat detection and devise a strategy that will best fit in with your system.