[Loobylou]

So if a cow has twins and she has one of each sex, is the female always a freemartin? Not that I've got. Just wanted to know

[devonlady]

Not always but generally.

[Loobylou]

So How would you know if they were freemartins? Would you test at a certain age?

[landroverroy]

 Realistically you wouldn't bother testing, just fatten it for meat.

[Loobylou]

Ok that's fine, thanks

[SallyintNorth]

Realistically you wouldn't bother testing, just fatten it for meat.

Agree.

But treat and handle her like a heifer, because she may be fertile - so she may come a-bulling and if she's with entire males, could get herself pregnant

[Kimbo]

Realistically you wouldn't bother testing, just fatten it for meat.

Agree.

But treat and handle her like a heifer, because she may be fertile - so she may come a-bulling and if she's with entire males, could get herself pregnant

   well that is one beast you would certainly want to keep!

[SallyintNorth]

Some people think that a freemartin won't be a breeder, and therefore they can safely run her with uncastrated males and/or the bull.  I was simply making the point that you shouldn't assume that she won't be a breeder, so she could come a-bulling before you would want any heifer bulled, and if you don't treat her like any other heifer, she could be running with males you would not want fathering calves, giving you a teenage pregnancy with a non-ideal father.

[waterbuffalofarmer]

Am I correct in assuming that the heifer, IE freemartin, may not be infertile? I was told that almost all of them are

[landroverroy]

 No.
The assumption is that a freemartin is infertile because of the male hormones from her twin brother that entered her bloodstream before she was born.  
However - many things in nature are not absolutely guaranteed. Therefore, given the remote (but unlikely)  possibility that the heifer could get pregnant, it's better to play on the safe side.

[twizzel]

One of the cows in my partners herd is a twin, she's just had her 2nd calf 

[Backinwellies]

The big issue here really is no one would want to feed a cow for 2 years to find out its not fertile ... So practically you would assume a female twin of a mixed se Ed set of twins is infertile and fatten for meat.

[waterbuffalofarmer]

You dont necessarily have to wait two years for her to bull, some of my heifers have come bulling at one year. Thankfully i dont run them with the rest of the herd and bulls. 

[farmvet]

Some non breeders can be detected by vet exam eg short vagina, small/absent ovaries, but others may appear normal on scanning/ palpation but never breed due to eg absent oviducts. It is quite routine in this area to check any brought in cattle before bulling usually at the same time as bvd screening. You cant always be right though, one client has a homebred jenny with a 4" penis at the clitoris and she calves reguarly.

[SallyintNorth]

One of the cows in my partners herd is a twin, she's just had her 2nd calf 

Female twins are usually both fertile, of course - and for some reason dairy farmers seem very happy to have female twins, lol.

It's luck of the draw whether the female will be fertile if the other twin is a male.   But there's no doubt that some are.