there has been alot of topics about this and what i have seen you are thinking of doing alot of different animals. so what i thought would be cool was if you just made a randomly generated color scheme for all the mobs and then maybe there would be around 200 different pig colors on just one world where only like 10 mobs would be the same color and they would live in some sort of herd, that way if i find the most awsome black with blue mohawk then i can take 2 with me and kill the rest, and that way i could breed them and sell them because the chance that it would appear again would be really low.