"" is breeders' informal term for surgical techniques by which male livestock, such as bulls, retain their full libido (and related effects like sex pheromones that would be lost through castration), but are rendered incapable of copulation. This is done to stimulate and identify estrous females without the risk of transmitting venereal diseases or causing a pregnancy by a male other than the one intended for selective breeding. Animals altered for this purpose are referred to as teasers (teaser bulls, etc.), or gomers. Several methods are used. Penile translocation surgically alters the penis to point far enough away from its normal direction that it cannot manage vaginal penetration. Penile fixation permanently attaches the penis to the abdomen so that it cannot be lowered for penetration. Penectomy is the partial or complete removal of the penis.