My cousin is a producer and swears by this stuff. He makes both a human and canine version under the brand name Caneva (in Canada). Mostly sold for joint issues and bone regrowth support in osteoporosis.
[url=http://www.caneva.ca/]CanEVA - Home[/url]
I haven't tried it, so can't comment on the effectiveness, but I have met the elk and seen his operation. It is a renewable resource (elk grow and shed antlers annually and are not harmed by the farmers removing the antlers from them while in a young, velvet-covered stage). It is totally natural - they live in beautiful woodlands and pastures, are only fed haybales during the winter, otherwise they graze for their whole lives. I have eaten his elk burgers and sausages - they are awesome!