Because you see the visual signs of heat does not necessarily mean you have to AI them then and there.

Sometimes they may be coming on, and thus not ready to be bred yet, and sometimes they are just after heat and you are too late.

With each missed heat costing a dairy farmer €250 and a suckler farmer €149, it is vital that you not only know the signs of heat, but what stage of it they’re at.

Coming on

This stage of heat lasts 6 to 10 hours. You can tell that she is coming into heat but aren’t quite ready to be bred yet.

Crucially, she will not stand to be mounted. This is the most obvious signifier if a cow is in heat or not. However she may try to mount other cows

Other signs she may be coming on is restlessness, and her making a lot of noise. Physical signs may include a slightly swollen, red and moist vulva.

She will smell other cows and other cows (and bulls) will smell her; there are pheromones in the urine that signal when a cow is in heat.

young teaser bull with Moocall heat collar smelling cows for heat detection

Standing heat

It is at this point that your cow or heifer can be mated with. This stage of heat generally lasts 6 to 24 hours, 18 on average.

Like the first stage of observable heat, the cow’s vulva will be red and moist. However if there is a clear mucus discharge this is an indication that she is in the next stage of heat and can be mated with.

She will also try to mount other cows, like the previous stage of heat; but unlike the first stage she will stand to be mounted by them.

cow standing to be mounted by other cow

Image source

A cow will behave differently during her standing heat, and will be nervous, excitable or restless. One situation you may notice this in is when you’re moving your herd from the shed to the paddock or vice-versa; she may lead the herd or lag behind.

Another sign of heat dairy farmers may catch, is that she could hold up milk.

After heat

When 24 hours pass after the first heat, it is too late for the cow to be mated and you must wait for the cycle to pass.

You know this will be the case when the cow will no longer stand to be ridden. Soon afterwards she may still smell other cows, but in the vast majority of cases she will not try to ride them. Clear mucus discharge will continue to run from her vulva.



Your cattle may not display all of these symptoms while they are in heat, and because of that it can be hard to come to a verdict on what point they’re at.

One way to look for more signs of heat in an inconclusive heat is to move her into your bulling herd.

If you think she is displaying all the right signs, inseminate her. However, only do it if she has had no matings in the last 20 days.

If more than one in ten of your heats were recorded as inconclusive, you should consider reviewing your heat detection practices.

More accurate solution

The Moocall HEAT system is a far more elegant solution to all of this; it gives you a startlingly high accuracy rate when it comes to heat detection, and it minimises the time you spend looking at your herd for signs of heat.

As well as that, Moocall HEAT can do the one thing most farmers miss – it can detect silent heats in your cows and heifers. Missed heats can be costly, and this system will put €250 back in your pocket if you’re a dairy farmer, €147 if you’re a suckler farmer. Per cow.

Moocall HEAT collar for heat detection

Learn more about Moocall HEAT here: