Effect of immunological castration on sexual and production characteristics in male cattle.

Ten male Friesian calves were actively immunised against luteinising hormone releasing hormone and their production compared with 10 Friesian steer calves. Five of the immunised calves responded poorly (group 1); the other five responded well (group 2), resulting in high antibody titres, low serum testosterone levels, involuted testes, reduced libido and semen production, and docile behavior. The castration effect lasted approximately six months before reversion to near normal male status. This temporary immunocastration failed to affect seriously performance until slaughter, and liveweight gain was substantially better in this group than in the steers. Carcase traits were similar in groups 1 and 2, but the lean content in both was considerably greater than in the steer carcases.