No, it isn't safe to feed horses anything that isn't regular in their diet. I USED to give my horse m&m's. I think I did it like twice, and stopped, it isn't safe, and they could get very sick. I'm actually surprised the horse would even eat meat. I've offered my horse other food besides fruit and veggies (not with the intentions of giving it to him, but just curious), but he doesn't even seem interested in it.