I heard flax seed oil is supposed to be amazing
but I haven't had the chance to try it yet.
A raw egg in their feed? That doesn't sound healthy! Lol I've never heard of it!
Maybe it's not a raw egg and I'm being silly.
I feed my horse a hoof supplement, and the biotin helps keep him shiny. He also gets regular corn oil in his feed, and I've noticed a difference (it helps if you start the oil before their summer coat grows in under the fuzz). The best thing I've found, however, is good ol' fashion currying. After my horse is done his work, I take everything off (halter included) and he stands for a half hour to an hour while I curry the crap out of him! He LOVES it, and he's not a horse that usually enjoys brushing. After his workout he's hot and his pores are open, so it gets rid of loose, dead hair easier and helps work sebum (the hair's natural oil) to the surface to make it shiny. It's a lot of work and effort and I'm aware that not everyone has that kind of time, but it's definitely the best thing I've found :)