Colour yet again! - dominant and recessive colour genes

Elizabeth · Post by **Elizabeth** » Fri Oct 14, 2005 11:09 pm

Ok I know that this question has been asked before, but I am a little slow in the science department. If a black cow, who's sire carries dun, is bred to a black bull, will the calves aways be black? if bred to a dun bull ...what colour and what % of the time? If a dun cow, dam whole dun and sire black carrying dun, is bred to a dun bull, will the calves always be dun? a black bull ....always black or what % Next ? I have will be about red....but I really don't want to get confused!!! Liz

Duncan MacIntyre · Post by **Duncan MacIntyre** » Fri Oct 14, 2005 11:32 pm

Think of a Dun Dexter as a black one which has two recessive genes stopping the black being really black. It needs one of these from each parent, so it is dun/dun. A Dexter which is black but carries dun is dun/0
so dun/dun x dun/dun will give 100% Dun coloured calves.
dun/dun x dun/0 will give 50% dun, 50% black carrying dun
dun/0 x dun/0 will give 25% Dun, 50% black carrying dun, and 25% black not carrying dun.

Dun can

Elizabeth · Post by **Elizabeth** » Fri Oct 14, 2005 11:49 pm

Well that was the first time a science lesson made me laugh, Dun Can! I understand that, I think. Does it automatically follow that a black who's grandsire was dun, carries dun? or not? and why does 'red' look like dun? How can you tell?

Duncan MacIntyre · Post by **Duncan MacIntyre** » Sat Oct 15, 2005 12:12 am

One thing you can be sure of is that if one of the parents is dun, then the offspring must carry dun even if they are black. It is entirely possible for the dun gene to pass through several generations without showing - it will only show itself when it is inherited from both sides.

On the red versus dun issue, I must say I have never seen a dun I thought was red or a red I thought was dun. There is quite a variation in red, from what I like to call a "good" red, which is of course just my opinion, and that to me is an even colour over the whole animal, no darker head and neck. I am not a geneticist and out there lurk real geneticists, maybe one will come in on this. I think there are different red genes, and I wonder if the reds which confuse people with dun are really reds with darker head and neck which also have tw dun genes to modify the blacker bits of the red - but I do not know if that is true.

The genes for red and Dexter dun can be checked from DNA the same as bulldog genes if you really want to know if a black one is carrying dun.

Duncan