Freemartins

[Callieslamb]

I read alot about freemartins on this forum. Are they really that common? My dad was a dairyman. I spent my life around cows. In 40 years of dairying, I have only known about 4 sets of twins to be born. My dad was an AI guy also. Are twins more common now? Is there something the larger dairies are doing to make twins more common - or did I live in a bubble all those years?

[ladycat]

Interesting question. I grew up around beef cattle, and I don't remember seeing twins more than a couple times.

Maybe I lived in a bubble, too.

[r93000]

We've only ever had 2 true freemartin heifers (that we knew of) show up in our families herds in my 20 years with cattle. One was not an official twin born from a heifer. They were both very tasty

Twinning rate depends on breed type, nutrition, genetic lines, and even uterine capacity so we had certain cows that had twins regularly and their offspring continued the trend for usually one generation, which raised our twin herd rate, but only periphally (if that makes sense). We generaly kept beef twinners so long as their milk capacity was sufficient. Dairy twinners stayed if they carried large healthy twins and got shipped if they carried small twins or if they consecutively had difficult births.

DIZYGOUS (not an identical or split cell)-Beef breed twinning rates are less that 1% and dairy rates run between 2.5-5% depending on breed and season. Lactating cows have a higher rate of double ovulation. The other thing with twinning is that once a cow has had a set of twins, so long as her nutrition is adequate, she is more readily able to carry another set to term since her uterine capacity has already been enlarged.

So for beef breeds it falls somewhere around 1 in 200 births is twins and statistically only half of those is a male/female pair so you run the risk in beef of getting a freemartin 1 in every 400 births. For dairy breeds the range is much wider but we'll look at the high mid range figuring 4% twinning- 1 in 25 births is twins and statistically half would be a male/female pair which lowers the rate to 1 in 50 births runs the risk of having a freemartin (Please feel free to correct my math if is off).

It is a 92% chance of the male/female twins that the female will be a freemartin. Males can also be genetically freemartins, but I do not have statistics for those since they are generally not kept for any type of breeding purpose. Also, male/female, male/male, female/female twin rates can also be adjusted based on the statistics of the bull you are using- male sperm rates vs female sperm rates. If your bull throws mostly males, then your chance of a freemartin would be lower and vice versa if your bull throws almost exclusively females, less chance of a freemartin.

Just another thing to throw out there- As I said one of our freemartins was actually born in a singleton birth to a first time calver. This is the result of there initially being a male twin during the pregnancy, but it was not carried to term and either absorbed or aborted without the loss of the female twin. (This type of twinning doesn't even figure fully into the statistics, but it can be a fair occurence that twins are conceived but not both carried to term - more uterine capacity, nutrition, etc in play) So even if you are purchasing a singleton birth heifer, it is not automatically guaranteed that she is not a freemartin.

[topside1]

At the dairy auction, I'd say out of 100 new born calves 2 will be non-breeders...Topside

[Jennifer L.]

I've read the "official" number for twinning in Holsteins is about 5%. My herd usually ran 10% twins. It's really just a genetic thing that can be bred for or against, and for some reason it was higher in my herd. This was over a very long period of years, 30 or more as it was my parents' herd before me. We normally had four or five sets a year with a 40 cow herd.

Twins are undesirable in cattle. If you aren't there when they are born you can lose one to breech birth, plus there's the freemartin problem associated with heifers born co-twin to a bull. Freemartins make EXCELLENT beef though. Best meat I've ever had.

Jennifer

[Callieslamb]

Thanks. I didn't know that twins were so common in cattle.

[Chixarecute]

Sometime in the last 2 years I recall reading a farm paper article that stated the incidence of twinning is increasing in the dairy breeds...may be connected to selection for increased production.

When I was pregnant with #2, my obgyn said "Everyone thinks twins are so cute, so efficient. A twin pregancy is a big worry due to the potential for so many complications." Cattle probably have less complications during the pregnancy, but at birth...

[ladycat]

Originally Posted by Chixarecute

Sometime in the last 2 years I recall reading a farm paper article that stated the incidence of twinning is increasing in the dairy breeds...may be connected to selection for increased production.

I wonder if there's a connection with the hormone shots they give them for increased milk production?

Or I should say, *were* giving them. I think hardly any dairies are still using those shots as of the last year or two.

[Callieslamb]

I wonder too. My dad never gave anything to his cows. He did some selective breeding and had a very nice herd when he had to sell out due to his failing health. Twins were so rare, that worrying about freemartin wasn't something I was raised with.

[sammyd]

Considering that the hormone had not much to do with reproduction and was commonly given to cows that were not bred back to lengthen their productivity I wouldn't think it had anything to do with it.

I would go with the breeding for increased productivity haviong a hand in it.