why do some bulls have rings in their noses
Nose ring (animal) The nose ring assists the handler to control a dangerous animal with minimal risk of injury or disruption by exerting stress on one of the most sensitive parts of the animal, the nose. Bulls, especially, are powerful and sometimes unpredictable animals which, if uncontrolled, can kill or severely injure a human handler.[2][3]
Arrector pili muscle Contraction of the muscles has a number of different purposes. Its principal function in the majority of mammals is to provide insulation: air becomes trapped between the erect hairs, helping the animal retain heat. Erection of the porcupine's long, thick hairs causes the animal to become more intimidating, scaring predators. Pressure exerted by the muscle may cause sebum to be forced along the hair follicle towards the surface, protecting the hair.