I remember reading a James Herriot (of All Creatures Great and Small fame) story some time back about where he talked about a bull calf he had delivered.
The calf became his best friend...when he drove up, the calf would come running up and gamboled about him...even well into adolescence, just the chummiest animal that could be.
He went for a stretch of some months where he didn’t visit that farm, and when he did, sometime in that interval, the calf had turned into an adult bull.
He had been called to place a nose ring in the bull, if my memory serves me correctly.
When he approached it, He was startled by the dramatic change in the animal, even apart from being fully muscled and brawny...it reeked of aggression to the point of hatred. When he looked into it’s face, the calf with the doe-eyes was long gone, and a “glittering malevolence towards all things human” (including him) now looked back at him.
IIRC, the bull, his former chum, nearly killed him when it got loose as he was performing the procedure.
As proficient as man thinks he might be at husbandry, We will never breed the Auroch DNA out of the Bovine. They will always retain a great percentage of the primal instincts of their wild and dangerous ancestors. I think it is the same with all “domesticated” animals, they can and will always revert back to their wild ancestral temperament at times. :)