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Genetics of color patterns

Grassfarmer

Well-known member
Can someone explain to me how the color pattern genetics work with regard to white socks/bell brows/shorthorn type markings? We are starting to get more of these calves turn up in our Luings (which have shorthorn in their background) but it always seems to be in female calves. Will I start getting male calves like this too in time or does it only go through the female side?
Examples.
DSC02821.jpg

One cow of this pattern I kept breeds this color on females, solid red on bulls.
DSC02823.jpg
 

randiliana

Well-known member
What you are seeing is the recessive spotting gene, in general. There are other genes involved which detirmine how much white, and just where the white would be located, I don't think much is understood about these modifying genes.

Basically, the recessive spotting gene works the same way as the red gene does. A cow can carry it, but not show it, and she may never throw a spotted calf if she is only bred to non carrier bulls or even to hetero bulls. If she shows the spots, then she is Homozygous for the gene. So far as I know, it is not sex linked at all, so if you haven't had any bull calves with spots, that is just luck (or bad luck, depends how you look at it). Sooner or later you should end up with a spotted bull calf.
 

Grassfarmer

Well-known member
Thank you randiliana, That helps my understanding a little. The only bit I don't understand is if the cow showing these markings in homozygous for that trait shouldn't that always result in her having a spotted calf? In fact she had a solid red calf last year off the bull that is leaving the spotted calves this year.
I'm not real clear on this aspect of genetics - seemingly even simple things confuse me. I bought a bunch of tan Char x cows last fall bred black Angus and 20% of the calves are horned :roll: :roll: Now I don't think that's supposed to happen.
 

randiliana

Well-known member
Grassfarmer said:
Thank you randiliana, That helps my understanding a little. The only bit I don't understand is if the cow showing these markings in homozygous for that trait shouldn't that always result in her having a spotted calf? In fact she had a solid red calf last year off the bull that is leaving the spotted calves this year.
I'm not real clear on this aspect of genetics - seemingly even simple things confuse me. I bought a bunch of tan Char x cows last fall bred black Angus and 20% of the calves are horned :roll: :roll: Now I don't think that's supposed to happen.

The spotting gene is recessive so look at it this way

S=solid color (dominant)
s = spotted(recessive)

Your cow is ss which is spotted
your bull is Ss which is solid colored

ss x Ss =

50% Ss (solid colored)
50% ss (spotted colored)

It works exactly the same as the Black and red genes do.

I'd be betting that that Black Angus bull wasn't a purebred :wink:
 

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