I give it to the cows, they love it. Only one of them is brave enough to come up to the feed bin while i'm standing there, so only one gets most of it. The brahman heifers are getting pretty quiet too.
Actually if i have a keg thats not quite right and i got a fermenter back log i'll throw a few litres of beer in the feed trough, they love that too, really good for them too. I don't do that too often because they get too friendly after they've knocked back 10L of beer, plus i hate throwing away beer.
The dog likes spent grain too, he chewed threw one of my biab bags to get at it once. He has a little ritual where he eats as much as he can, then throws it up and eats it again, must taste better after he's marinated it. The dog doesn't get any beer, hops are bad for dogs apparently.