Actually all protein originates in plants, so getting your protein from animals is really just inconveniently (and with a great loss of energy technically speaking) going through a middle man.

What's more is that although your backyard chickens aren't having babies themselves, I guarentee the farm where you first attained your chicks (or any company that sells commercial eggs) will consider it routine practice to cull male (non-egg-laying) chicks, as they are neither profitable for eggs nor being reared for meat. We typically use different breeds of chickens for that.

I would hope this information changes your perspective somewhat?