I always thought that if a kids dam and sire are blue eyed then that kid is homozygous for blue eyes but tonight I was told otherwise. Does any one know how blue eyes work?
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You're getting closer Nicholas, but not quite ... since we don't have genetic testing to figure out what kind of genes a goat has, we have to wait and see how their kids turn out. If your doe keeps throwing blue-eyed kids, regardless of whether she is bred to a brown-eyed or blue-eyed buck, then at some point, you can assume she is homozygous.
If you have two parents with blue eyes, and they came from parents who had a blue-eyed and a brown-eyed parent, then each of them has one gene for each color, so the kids will be:
25% brown (received brown eyes from both parents) like one of Janel's triplets
50% blue (received a brown eyed gene from one parent and a blue-eyed gene from one parent)
25% homozygous blue (received blue eyes from both parents)
Margaret is correct that the longer you breed blue-to-blue, the greater the odds of breeding out that brown-eyed gene, but it can remain hidden for several generations. It's a crap shoot ... kind of like flipping a coin over and over again. You could get heads five or six times in a row ... just like my bull threw five polled calves in a row.
I thought that is a blue eyed goat was bred to a blue eyed goats and the kids came out they were homozygous, but I think I know what you guys are saying now. If a blue eyed goat is bred to a blue eyed goat then then the kids will be blue eyed but that doesn't mean they are homozygous. In order for them to be homozygous both their parents have to have blue eyed AND their parents parents. Correct? I have a doe who I thought was homozygous because both her parents were blue eyed, she was too, and all three of her kids have had blue eyes. But I think she still carry's the brown eyed gene because her paternal grand sire is brown eyed and perhaps her maternal grand sire or dam are too. I am so glad someone corrected me. I guess if this was the case we would have a lot more blue eyed goats!
So, if someone bred blue to blue for a couple of generations then they would PROBABLY start to produce homozygous kids? Would stand to reason if blue is dominant that non-blue would pretty much be bred out pretty quick, wouldn't it?
The thing about homozygous blue eyes is that you won't know a goat has them until they've had a lot of kids. Typically, no one feels safe saying a goat is homozygous until they have at least ten offspring, ALL with blue eyes. But even then, if #11 has brown eyes, you've just been lucky on those last ten. We had a bull throw 5/5 polled calves, even though I know he was not homozygous because his mother was horned.
You have to remember that a goat has two genes for everything -- one from mom and one from dad. So, if you breed a blue eyed goat and a brown eyed goat, you will get kids that have a gene from both parents. The brown-eyed goat can only pass on a brown eyed gene, but since blue eyes are dominant, if the blue-eyed goat passes on a blue-eyed gene, the kid will be blue eyed, BUT it will have one gene for blue and one gene for brown, and it could pass either of those genes onto its kids.
I had a doeling that both parents had blue eyes and she came out with brown. Both her sisters had blue eyes though. So it is possible!
Here is a link to another discussion on here. Deborah shared a link that will probably help answer your question(s).
http://nigeriandwarfgoats.ning.com/forum/topics/polled-blue-eyes-nd...