It is an old non animated movie around the 70s or 80s?

the movie is about a white bull that is strong willed. the bull and a boy somehow get lost in the wilderness and are attacked by some dangerous animals (lions or pumas or something like that). the bull protects the boy by letting him ride on his back while the bull kicks the animals to get through. The bull had never consented nobody to ride him. I think that the bull was the meanest in bull riding rodeo.