The Silver (Dapple) Gene

Just recently, I've dived (just a short dive though) back into horse genetics, colors, and research. This time, however, I have a specific area that I'm gaining knowledge on- the Silver (Z^Z gene).

It really is an interesting gene. Similar to the Cream and Champagne genes, it is a dilution gene. However, it goes a smidgen more complex than just that- the Z^Z allele will only affect eumelanin; that is, black hair color. The only other melanin in horses is pheomelanin (the red/brown/yellow coloring), and that is left unaffected.

Before I get to the fun part, there are a few more factors to cover. The Z^Z gene is located on horse Chromosome 6, in the PMEL17 gene. It is a simple dominant allele, so if a horse has this trait, it will appear in the phenotype. The one exception to this is if the horse is a chestnut, in which case it'll take either breeding or testing to tell.

EDIT: The gene may not be a simple dominant allele. Please read my later blog post on it! 

By breeding, let me use this example to explain what I mean: If you breed your chestnut mare to a black stud, and produce a silver bay, you then know that your mare carries silver-positive allele.

Sure, one may think that breeding to find out true color (which one cannot always find through this method) saves you...say, $40 by not testing. However, if color is an element of your breeding program, and you can scrap together 40 bucks, do it. It isn't that hard- just follow the instructions here.

Okay, yay! Time for the fun stuff. :) Let's start with a few base colors + silver gene = the answer.

Black + Z^Z = Chocolate (or Blue) Silver
Bay + Z^Z = Bay Silver
Chestnut + Z^Z = Chestnut (but carries the Silver allele)

And of course, there are combinations of base color + Silver + other dilution or extension genes. However, I'll save that for another time.

Do you remember the Miniature mare that foaled out this June? She's actually a silver, as she has all the characteristics that the Silver allele elicits, and her sire had the allele. I'm almost certain that she's a seal bay silver, but nothing's been verified.

If you don't want to go digging through my awesome blog posts to find the picture of Bunny, here she is. And who knows, maybe Dove will be a Silver carrier as well. (:

Bunny, a Silver Dapple mare