Yep I feed my hens meat scraps, other food scraps, and left over milk. I used to work on a farm where we slaughtered our own animals and any leftover guts or scraps got thrown to the laying flock or pigs.Personally, I am a fan of feeding animal protein to appropriate animals like chickens, dogs and cats. Chickens. are not herbivores despite the current Perdue ad. Of course if that is all that is available, they will do fine. I toss leftover bones to the chickens to pick clean. Recycling at it's best.
Meat sources are a complete protein, with all the essential amino acids.