This message is from: David Hagen <[EMAIL PROTECTED]> Mark,
I'll take a stab at trying to explain how the color genes work, though the article that Jean reference is also a great starting point. I figured out how the color genes work by looking at them one at a time, so that's how I'll try to explain them. Since all Fjords carry the gene that produces dun I am going to ignore that gene and focus on the other three genes that impact color in Fjords. The gene that produces brown is usually called "A". The gene that produces grey (black) is located on the exact same spot on the DNA strand, except that it is a recessive from of the "A" gene. Therefore it is usually called "a". For the recessive "a" gene to do what it does (produce grey/black) there must be two copies present, so at that location on the DNA strand a Fjord looks like one of the following combinations... A brown Fjord that doesnt' carry grey/black would be "A-A". A grey Fjord would be "a-a". A brown fjord that carries the recessive grey gene would be "A-a". It will look like a brown horse, but it could pass along either the "A" gene or the "a" gene to it's offspring. This is what all three of your Fjords being discussed appear to be. You asked "How can a brown pony carry only black genes? I thought they had to have a brown gene to be brown?". You are right. A Brown horse does not carry only grey/black genes. You horses carry one "A" (brown) gene and one "a" grey gene. They are A-a. The odds are 50-50 that your brown stallion will pass along his grey gene. The fact that Leo has produced a grey foal every time is very unusual. It's like flipping a coin - each time you flip it you have a 50% chance of getting heads. In this case Leo has gotten heads (passed along his grey gene) six times in a row. The odds are against it, but it can happen. Likewise, the odds are 50-50 that either Jordan or Elli will pass along their grey "a" gene. The odds of getting a grey foal when breeding two browns that carry grey are even smaller -- 25% (.5 x .5 = .25). Each breeding has just a 25% chance of producing a gray. Your breedings that have resulted in greys have gone against the odds. The fact that it has happened multiple times really goes against the odds. To use the coin analogy again, it's like having two people flipping two coins at the same time. Each person has a 50-50 chance of getting heads with their coin. In your case, both individuals have gotten heads every time they have flipped their coins together. The odds of that happening are very small. Assuming you like greys you can consider yourself very lucky. Now on to the next gene. The red gene is in a different location. The gene that is present in a brown horse is usually called "E". The gene that produces red a recessive form of the "E" gene and, terefore, it is usually called "e". For the recessive "e" gene to do what it does (produce red) there must be two copies of it present, so at that location on the DNA strand... A brown Fjord that doesn't carry red would be "E-E". A red Fjord would be "e-e". A brown fjord that carries the recessive grey gene would be "E-e". It will look like a brown horse, but it could pass along either the "E" gene or the "e" gene to it's offspring. This is what all three of your Fjords being discussed appear to be. Now here's where things start getting complicated. We are looking at two locations on the DNA strand. A brown dun that does not carry any color would look like this: A-A, E-E. A brown dun that carries BOTH grey/black and red would look like this: A-a, E-e. A grey dun that does not carry red would look like this: a-a, E-e. Here's a really tricky one: What happens if a fjord is a-a, e-e. Is it grey or is it red? The article gene referenced seems to say that the horse would be red. The e-e combination trumps the a-a combination. (Wouldn't it be cool if the horse was a mix of red and grey? Purple?) Elli's mother was red, so she was definitely an e-e. Her mother had no choice but to pass along one copy of that "e" gene to Elli, but since Elli is brown we know that she got an "E" gene from her sire and she is E-e. Likewise, since she is brown but has produced grey foals we know that she carries grey, so she is A-a. So, Elli is definitely A-a, E-e. Since Jordan is a brown horse who has produced grey foals we know that she is also A-a. She probably got the "a" gene from Ellie. Since Jordan has not produced a red foal yet we do not know if she inherited Elli's "E" gene or if she inherited Elli's "e" gene. You could have Jordan genetically tested to find out if she carries the red "e" gene but, short of doing that, there is really no way to be sure if she carries "E" or "e" unless she produces a red foal. There is one more color factor to throw in -- the cremello gene. Unlike red and grey/black, it is not a recessive. A horse only needs one copy of the Cr gene to dilute the base color of the horse. The "neutral" version of it is C. A red or brown Fjord is C-C. If an otherwise brown horse carries a Cr gene (so that it would be C-Cr) it will appear to be white/uls. If an otherwise red horse carries a C-Cr combination, then it will appear to be yellow. If two C-Cr horses are bred together, then they might both pass along their Cr gene and produce a foal that carries Cr-Cr. No matter what the base color is a horse that carries Cr-Cr will be white with blue eyes. I hope this helps or, at the very least, that I didn't confuse you even more! Best regards, David Hagen
