Polled dominant gene?

SuperDog · #1 03/14/10, 05:38 PM

I have a cow that is half holstein and half angus. She was bred AI to angus. She had a calf last May, and today I notice he is starting to grow horns. Now they are pretty small, but they are still there. Being that he is 75% angus, shouldn't he be polled? I thought the polled gene was dominant.

Mike

cowkeeper · #2 03/14/10, 05:41 PM

Probably scurs..they never become 'real' horns and are loosely attached to the head.ck

myersfarm · #3 03/14/10, 07:55 PM

did you have her AI 'ED OR WAS SHE BRED that way when you got her

SuperDog · #4 03/14/10, 08:02 PM

I had her AI'ed. I have the angus bull name somewhere. The cow that gave birth to the calf also has those scurs, but I thought being the calf is 75% angus, that there should be no scurs or horns at all. Not a big deal, just found it strange.

Thanks for the responses.

Mike

ksfarmer · #5 03/14/10, 09:07 PM

a small percentage will have horns, donno why. They usually are smaller and softer than full horns tho.

genebo · #6 03/14/10, 09:24 PM

Scurs are carried on a different set of genes than where horns are carried. If the cow has horns, it suppresses the scurs. It's only when she doesn't have horns that the scurs can grow.

So your Angus AI semen appeared to have done it's job and given you a polled calf. Unfortunately, the calf inherited scur genes and the polled trait allowed the scurs to express themselves.

If they are objectionable, you can actually remove scurs by the same methods you would use to dehorn a cow.

Genebo
Paradise Farm

SuperDog · #7 03/15/10, 01:14 PM

Interesting.... That helps a lot genebo. I don't mind them there. He is going to freezer camp this fall. Now I know how it happened tho. I didn't realize that scurs and horns are on different genes. I thought they would have been the same... I guess I have a lot to learn about genetics.

Mike

ArmyDoc · #8 03/15/10, 03:02 PM

The polled gene is dominant, so if they have it, they are polled. If they are homozygous (most purebred angus), all their calves are polled. If they are heterozygous (one gene for polled one for horned) half of their calves will have horns if bred with a horned animal, or 1/4 with horns if bred with a Heterozygous polled animal, and of course if the other animal is homozygous polled, none of the calves will have horns.

So, if the calf has horns, either the Angus bull was heterozygous for horns (unlikely) or she was in acutality bred to a different bull (AI didn't take, and she was bred after, or she was already bred befor AI)

Scurs are different. They sex linked, recessive, carried on the X chromosome. In males, it only takes one scurs gene to to express the scurs (because it's carried on the X chromosome, and there isn't anything to counter it on the Y chromosome) in females, it takes two - ie they have to be homozygous to have scurs because they are recessive.

So, if the bull calf has scurs, the mother cow carries the scurs gene (the angus bull doesn't carry it, or it would have had scurs itself)

Here's a link that goes into this in much greater detail:

http://www.cals.ncsu.edu/an_sci/exte...6/aug96-3.html