I'm not sure if that's true. The FDA announced that it would ban poultry litter in feed twenty years ago, and even then I'd be surprised if it was all that common. Poultry litter contains all sorts of contaminants, including antibiotic residues. Antibiotics must be withdrawn for a certain amount of time (depending on the species) before an animal is butchered or before its milk can be sold.
I thought I read somewhere that bird poop or bird litter is in cattle feed.
I'm not sure if that's true. The FDA announced that it would ban poultry litter in feed twenty years ago, and even then I'd be surprised if it was all that common. Poultry litter contains all sorts of contaminants, including antibiotic residues. Antibiotics must be withdrawn for a certain amount of time (depending on the species) before an animal is butchered or before its milk can be sold.