The Satin gene is found in rabbits I know. Satinizing basically makes the cornified layer of the hair shaft clear rather than pigmented, with a core of concentrated pigment instead of pigmentation spread through the entire hair shaft. Basically the same effect as painting clear nail polish over colored nail polish. It increases the shine.
Spent a whole hour today laying in a pasture, waiting for a sparkling vampire to show up. Alas, I woke up and looked over, only to find a mound of horse crap. Sigh.