Why does Mingo spend so much of his time alone?

Mingo has a different relationship with the master that sets him apart, as he is valued for his ability to train the chicken to fight. Mingo also values his privacy, and in his position, wants to keep his secrets to himself. He doesn't want anyone learning his secrets and supplanting him in his position.

Near the end, why does Mingo want George to have his bucket of secret feed?