Our chickens would never eat the butchering offal, either from rabbits or hogs
However, I feed them TONS of meat scraps ( a little at a time, lol). I do this mainly during the winter because during the summer they are pastured. The only problem I have with doing this is that during really cold weather the meat/bones freeze. The chickens will still peck at them, but it takes a bit of work to get the frozen meat off of the bones.
I tried something different this year- I had a couple of skinned raccoons in the freezer so I cut them up with my sawzall into pieces which would fit in an old crockpot. I have been cooking them overnight, along with any other kitchen scraps that we save for them, and in the morning the meat falls right off the bones. I mix it with the lacto-fermented chicken feed and place several bowls/dishes around the coop. The chickens go crazy for it.
I have one more meals' worth of the raccoon, after which I will start feeding them meat scraps from our processor, which I get for free.
To the OP, I also feed venison during hunting season.
eta: since I cook the meat until it is falling off the bone, I do not grind it. But if I had a lot of it at one time and intended to feed it raw, I would grind it, mainly to ensure a fair distribution amongst the chickens. I have a mixed flock of different ages and the little ones can't really compete with the bigger ones if I just throw chunks of meat into the coop.