Dominant Traits in Goats (OP: 9/17/2013)

A lot of people know some goats are born polled (hornless) and some are born with blue eyes. But SO many people don’t quite understand how this works!

I’m going to use “X” to denote both polled and blue eyes, because they are both a dominant trait, and interchangeable for the sake of this bit of a genetics lesson.

Let’s say you have a doe who exhibits X and a buck who doesn’t. You breed them.

Xx stands for the doe. This means she exhibits the trait (ie blue eyes). xx stands for the buck. He does not exhibit the trait.

If you breed Xx with xx, because it is a DOMINANT trait, and not recessive, you stand to get:

50% Xx
50% xx

In clearer terms, each kid has half a chance of exhibiting the blue eyes. Each kid also has half a chance of having plain eyes.

Now, you breed a Xx with a Xx. Two blue eyed goats.

This means you get 100% blue eyes right?

Wrong.

Because this is a dominant trait, both goats most LIKELY carry the brown eyed/horned gene as well. This means you get:

50% Xx
25% XX
25% xx

But wait, what does this mean? There’s three results.

Xx is obviously a blue eyed kid. xx is a brown eyed kid. So what is XX?

XX is a homozygous blue eyed kid. The homozygous means that it carries two copies of the blue eyed gene. This means if you breed a homozygous goat, all of its offspring will have blue eyes.

Now, I am not 100% certain homozygous blue eyed/polled goats exist. They should. Doesn’t mean they do.

Confused yet? It’s okay, it just takes some practice.

But let me get some things straight.

Your goat cannot CARRY the polled or blue eyed gene without exhibiting it. There is NO non-visual heterozygous for these traits, because they are dominant.

If you breed a blue eyed/polled goat to a blue eyed goat/polled goat, you can STILL get brown eyed/horned kids. You’re more likely to get what you’re seeking, but each kid still has that chance of the draw.

Hope this helps. I’ve seen one too many comments about “carrying” such and such gene or “guaranteed to have such and such gene kids.”