Variation in hormonal feedback and reproductive performance in rams of different genotypes from birth through puberty

Comparative experiments were carried out for elucidate the mechanisms that establish and control sexual behaviour of rams. Fifty-four ram lambs 2 to 24 wk of age were used for each of two genotypes and their crosses. The genotypes examined were the highly fertile nonseasonal D'Man breed and the low fertile seasonal Timahdite breed as well as the crossbreed of these two genotypes. Morphological, spermatological, ethological and endocrine parameters were compared. There seems to be a breed-dependent difference in the luteinizing hormone (LH) releasing pattern after gonadotropin releasing hormone (GnRH) stimulation at a specific prepubertal time period. This in turn reflects a breed-dependent difference in behavioral response in similar stages of physical maturation. The difference in behaviour is much more marked than the difference in physical characteristics.