Champagne is easy, it's a simple dominant gene. This means a horse either shows it, or it doesn't have a dominant copy. Horses who are homozygous (CHCH) look no different then heterozygotes (CHch).
It's the why part that is so interesting! The Champagne gene causes dilution of the pigment producing ability of cells. In other animals (it's well documented in mice) this gene is responsible for eye pigment. Interesting that champagne came up in comments a few days ago in regards to eye color! Seems that is the main function of this gene.
Now, the "why" part gets a bit technical. What basically happens is that the pigment cells are supposed to "take in food" and "put out color pigment". At least that's what normal cells do. In Champagne, the cells are on a diet. The molecules that should enter the cell are not easily able to enter, and thus, the pigments produced are, well... deficient of everything they need. This means weak pigment for both red and black. Because these pigment cells are all over the body, all pigment, from eyes, to skin, hair, and hooves, is affected.
Why the shine? Well, no where has any one seemed to cover that. It's my personal opinion that it's the shade of color, and they way human eyes pick up reflections of light. Red horses have more shine then grey horses, as an example. Not all Champagnes are shiny. Mine is in the middle of the spectrum, but I have seen both shiny and dull coated champagne horses.
In past generations, Champagne horses were often mistaken for creme dilutes. Many gold Champagnes (chestnut with Champagne - ee ??(unknown agouti) CH?) were thought to be palominos. This confused a lot of breeders as to the inheritance of the gold colored horses. I have also been asked by "old timers" if a palomino was "pink skinned or dark skinned". I suspect that this was how to differentiate between Champagne and Creme before people knew that DNA even existed.
Of course, I'm so amazed at how many breeders knew there was a difference! I'm not sure I would have been so astute!
Now, Champagne dilutes both black and red pigment in a horse. My filly shown above is genetically:
E? Aa Dd CHch. I know this because her sire was E? aa Dd CHCH while her dam was E? A? dd chch. Now... did those strings of letters make a bit more sense after reading the last few entries? If they didn't, the sire was a black dun champage (E? aa = black, Dd = dun, CHch = Champagne) while the dam was bay (E? A? = bay, dd = no dun effect, chch = no champagne effect).
Click for larger.
So, the dun would have also diluted her pigments. Dun can dilute both red and black pigment as well, so the additional dilution effect of champagne on top of that, means a silver and gold horse, in this case. Normal Amber Champagne horses (those without dun) tend to have darker points then this mare. I highly recommend this site http://ichregistry.com/colors.htm for pictures and more information on champagne. They explain it wonderfully!
Pearl on the other hand, is a very similar looking appearance on the horse. Both Pearl and Champagne are known for the metallic look, but Pearl gives a stronger shine then Champagne. Pearl is an incompletely recessive gene. Pearl can be traced through baroque bloodlines, including PRE and Lusitano horses. As a result, many of our stock breeds have this gene. It was first found in the Barlink bloodline of Paints!
This is a famous image of a striking pearl colored horse, taken from this link:
such as this black, creme, pearl carrying horse:
Often, genetics testing results will list a horse as PRL/N. Another way to write this would be PRLprl. In the case of pearl horses a horse exhibiting the homozygous recessive (prlprl) is what we would call a "pearl horse". A horse "without" Pearl would be written as "PRLPRL". Backwards to what is commonly seen in other genes.
So... ready for your test? What color is this horse?
EE aa crcr chch PRLprl
A bit of a tricky one!