Relaxation increases the relative length of the scrotum, thus moving the testicles away from body heat, In cold weather, the scrotum shortens and the testicles are held close to the warm body. A common cause of low fertility in bull is abnormal testicle and scrotal sac development. The testicles should be symmetrical, nearly the same size, and freely movable in the scrotum. Small size or degeneration often affects one testicle only and is a serious finding. There ar three basic shapes in beef bulls.
Bulls having a normal scrotum with a distinct neck generally have the best testicular development.
The normal scrotum offers the best opportunity for temperature control of the testicles. Often bulls with straight-sided scrotums are only moderate in testicle size. The straight-sided neck of the scrotum is generally the result of fat deposits that may impair proper thermoregulation. As bulls mature and lose condition, they will often develop a more normal scrotum. Wedge-shaped scrotums are pointed toward the bottom and hold the testicles close to the body wall.