Cows/Cattle/Early Estrus


Hello.  I know that normally heifers will have their first standing heat at about 14 months of age.  However, we have a young calf that just had her first standing heat at only 8 1/2 months old, much to our surprise.  As a result of this, I had to quickly get her separated from the bull since he was trying to mount her relentlessly.  That bull wen batjive crazy when I got her separated from him.

We pinned her up on Saturday morning, June 28.  I know that a heifer's standing heat can last between 12-18 hours, with 24 hours being a rare occasion. So we kept the calf pinned up for the rest of June 28 and all of Sunday, June 29.

This morning, June 30, She had been pinned up and separated from the bull for a total of 48 hours.  We thought she had plenty of time to get everything out of her system, so we released her back into the herd, but kept an eye on the bull to see what he would do.  Almost immediately, the bull came over to investigate her.  He smelled her butt continuously and acted like he was thinking about mounting her again.  So I instantly rounded her back up and she is pinned up once more.

So here's my question for you.  Is it possible for a cow to be in standing heat for more than 24 hours?  I'm hoping that the bull was only detecting remnants from her standing heat that might have dried up on her rump.  I thought for sure that keeping her separated from the bull for 48 hours was going to be more than enough time.  The bull threw a monkey wrench into that idea.

Any ideas on what is going on?  And why in the world would a calf that is only 8 1/2 months old be already having her first standing heat?

Thanks.  I look forward to your reply.

Good afternoon,

Ok, the bad news is that even though it's recommended that you breed your heifers for the first time at between 12 and 14 months, they actually DO come into heat much earlier!  Especially exotic or continental bred cows.  I've had them start their heats as early as 6 months old. Now a "bos indicus" or Brahman type heifer won't start their heat cycles until they are over a year old, and usually you can leave them with a bull and not worry about them getting bred too early.

If you want to keep heifers, you'll have to separate them from a bull until they're old enough to breed.  And I don't mean with one fence between them.. because almost any bull is going to try and breed them through a fence.

They go through different stages of heat.  First you'll see them trying to mount other animals.  That's when they are coming into heat.  Then they will let the bull mount them.. at which time you'll probably also notice a clear discharge.  That lasts for approximately 12 hours.  Then the after heat.. which a bull or a cow may still try and mount them, but they won't stand still.  A very aggressive bull will sometimes actually "breed" them at this stage, but they won't conceive this late in the cycle.

Since I'm assuming you don't want your heifer bred this young, I would suggest watching for her next heat, which should be 18 - 21 days.  If she comes back into heat, you're good.  If she doesn't, you'll want to give her a shot of Lutalyce, which will cause her to cycle again.

Good luck!



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Eileen DuJardin


I can answer most types of cattle questions, primarily beef types. Genetics, breeding, basic care, herd health and management, and showing. I'm knowledgeable in forages and feeding. Non emergency health and soundness questions. I am not a veterinary, and can't answer critical care questions. Call your local large animal vet for that service.


I've been a registered cattle breeder for over 20 years. My husband and I run a 250 acre cattle ranch in Texas. I've raised dairy cattle, commercial cattle, and registered and show cattle. I'm on our county Beef and Forage committee.

American Simmental Association. American Brahman Breeders Association. Falls County Beef and Forage Committee. Texas Farm Bureau

Associates Degree in computer science.

Awards and Honors
Many ribbons and placings in cattle showing, with most recent being: 2011 Fort Worth Stock Show, Senior Champion Simmental, and Houston Livestock Show Reserve Champion Senior Simmental.

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