Some people swear by it, some don't. I do - the product itself is mostly stabilized ground flax seed, but it also has psyllium (same stuff as in metamucil and SandClear) and other "stuff" in it.
We have a two year old colt that got in a really bad way - the more we fed him, the skinnier he got. He was a walking skeleton and covered with sores before the vet figured out he was unable to tolerate alfalfa - he wasn't allergic to it, but it was toxic to him. He also had a horrible habit of dumping his feed bucket and eating the feed off of the ground, and we have sandy clay soil. We tried setting his tub down inside a tire to make it hard for him to tip over. That worked - he couldn't tip over the bucket - so he resorted to pawing the feed out onto the ground and eating it that way.
We took him off the alfalfa, so now he gets soaked beet pulp and oats, with timothy hay pellets when we can get them. We started adding the Omega Horse Shine to all of our horses feed, and they have all blossomed! Colt has nearly doubled his weight and the sores are all gone. His coat has gone from dry and brittle to soft and luxurious. You can see a very well defined line in all our horses' hooves that shows when we first started using the product - even the farrier noticed. (He was suprised because he didn't think it had enough biotin in it to make any difference, but I guess with everything else it had in it, it was enough).
Our horses get 1/2 cup twice a day. It's plenty for the colt and the rest of the horses, but we give Dancer - my mare - and extra 1/4 cup because she's nursing and her filly, Rain, shares her feed bucket.
We really like the product, and the price is fairly reasonable.
Plain Old Dee, horses Dancer and Rain I believe in dragons, unicorns, good men and other mythical creatures!