My question concerns the religiosity of the chicken. Not only whether it was sacred, but whether there were any religions with rules about them. I was thinking about this the other day, and thought of the cats of Ancient Egypt, cows in India, pigs (pork) etc. and wondered whether the chicken was ever treated in any way by any religion. I've heard of Romans using sacrificial chickens, but I'm not sure. Thanks in advance! :)
Puranik Hinduism ( the one mostly in practice today in India ) does have a tiny bit of importance attached to chickens in an aspect of it. A goddess called “Bahuchara.” - an avatar of Shakti - is said to have a rooster as her vehicle.
Edit: you are mistaken, Hinduism considers a lot of animals holy. Horse for example, is one of the most sacred animals in ancient tradition. A successful horse sacrifice ( aswamegha ) could make you an emperor.