Fun Color Example to Try

[ctownson]

We have a customer who purchased the following two dexters:

1. Short legged black bull, that carries red and dun.
2. Long legged dun heifer, that carries red.

With this breeding, what is the probability the customer will get a short legged red heifer?

[laughingllama75]

Well, if that's what he wants then I would say about a 1% chance. LOL!
I know nothing about color genetics, compared to some. I would say the chance for red is there but the percentage?

[ctownson]

This combination comes up with some interesting percentages given the black bull and what he carries.

[Maple View Farm]

Ok, my sister had to help me and we did have to use google and we did have smoke coming out of our brains from straining. So this is what we found for the color.
50% for a black calf, 25% for a dun and 25% for a red. I'll have to try to figure out the genetic grid for the short leg/long leg thing.

[Maple View Farm]

We guessed that you have 25% chance for a short-legged calf and a 75% chance for a long-legged calf. So it looks like you're going to get a long-leg!

[ctownson]

Here is what (I believe) is the correct answer:

3/8's of the calves will be black (37.5%)
3/8's of the calves will be dun (37.5%)
2/8's of the calves will be red (25.0%)

Out of the red calves, 1/2 of them would be bull calves, so that brings us to 12.5% red heifers.
Of those, half would be short-legged. That gets us to 6.25% probability of a red short-legged heifer !

[Dahdo]

I got the same probabilities for color and chondro, so if you throw in sex (50/50), doesn't that make the odds of getting a short legged red heifer .25x.25x.50 or 3.125% ?? Alicia, you were pretty close?

Ok Charles, now did they have horns?? ;-)

[Dahdo]

oops, just posted before seeing your answer Charles. You are right, 50% will be shorties so I spoke too soon. Thanks for the brain teaser!

[ctownson]

Hi Dave. If 25% of the calves are red (we agree on that percentage), then half of those would be heifers (that brings us to 12.5% red heifers). Of those, half would be short-legged, which gets us to 6.25%. That was my logic - where do we differ?

They were both horned, so I avoided the polled issue. We could add that into the equation to make it even more interesting!

[Maple View Farm]

Post another question for us to figure out. Are you using the 4 square genetic graph? Help is newbies to figure it out. This is fun. the kiddo os helping too and this is good for her science skills. We have red, dun and polled in our herd. Any questions with those details would be cool.

[ctownson]

Hi Maple View. In this particular case you have to run through all 16 possible combinations of colors (4 x 4). Lets say B=Black, R=Red, and D=Dun (that should make it clearer for the youngster). So, the Bull would be BR on the first set and BD on the second set of genes.
The heifer would be RB and DD respectively. Now, map each possible combination - there are 16 total possibilities.

[Dahdo]

I goofed on the percentage of short legged animals--had it at 25%, but clearly the bull controls that one and its a coin flip.

I'm hoping to get some color diversity in my herd (like you have). I bred my red girls (who don't carry dun) to a e/e b/b bull this year and if/when i get some heifers with dun, I know a good dun bull who carries red that would give us good chances for all three colors.

[Maple View Farm]

Thanks so much. We homeschool so we love the fact that wonderful Dexters can be a school lesson. Now we are going to try to figure out what our calf crop will look like this spring. How fun!!

[Maple View Farm]

Thanks so much. We homeschool so we love the fact that wonderful Dexters can be a school lesson. Now we are going to try to figure out what our calf crop will look like this spring. How fun!!

[ctownson]

I also enjoy doing this when I know the colors. We don't test all of ours for colors, so sometimes you get a huge surprise like a red or dun calf when you least expect it!