EVALUATION OF ANDROGENIC AND GONADOTROPHIC ACTIVITY IN MALE TWIN CALVES BY ANALYSIS OF SEMINAL VESICLES AND SEMEN

Abstract

SUMMARY A series of experiments is reported on the evaluation of the androgenic activity in the male by analysis of semen and accessory glands of reproduction. In pubescent male twin calves the onset of the secretory function of seminal vesicles, as reflected in the appearance of fructose and citric acid in ejaculates, was advanced by injections of chorionic gonadotrophin. However, in much younger bull calves, gonadotrophin was incapable of evoking a similar response. On the other hand, testosterone injected into immature animals readily induced high secretory activity in the seminal vesicles. When androstenedione was injected into castrated bull calves, its androgenic effect on the fructose and citric-acid formation in the seminal vesicles was negligible by comparison with the powerful stimulating influence of testosterone. This probably explains why in young bull calves fructose and citric acid are not secreted by the seminal vesicles until the testicular content of testosterone markedly exceeds that of androstenedione. Underfeeding of young maturing bull calves not only delays the onset of secretory activity in the seminal vesicles as a result of decreased androgenic activity of the testes but also diminishes the responsiveness of the seminal vesicles to testosterone.