SUMMARY The androgenic effects of testosterone and dihydrotestosterone on the bovine seminal vesicles have been evaluated by (i) introducing the steroid directly into one seminal vesicle in situ, while retaining the other vesicle as a control or for the introduction of another steroid, or (ii) injecting the steroid subcutaneously into a whole animal, and examining the seminal vesicles after autopsy. When introduced directly into a seminal vesicle dihydrotestosterone oenanthate stimulated growth and the formation of fructose and citric acid, but the magnitude of the effect was not greater than that of a similar dose of testosterone oenanthate. When twin calves were injected subcutaneously, one with dihydrotestosterone propionate, and the other with the same dose of testosterone propionate, only the latter responded with increased output of fructose, citric acid and α-mannosidase in electro-ejaculated semen. But the seminal vesicles grew to approximately the same size in both twins. Parenterally administered bovine growth hormone produced a sudden but transient burst of secretory activity in the seminal vesicles, resulting in the appearance of fructose and citric acid in electro-ejaculated semen.

1. Experiments on three pairs of male identical twin calves have shown that underfeeding at 2.5–6 months of age, i.e. during the critical stage of sexual maturation, considerably delayed the process of puberty, as regards testicular androgen production as well as secretion of fructose and citric acid by the seminal vesicles. 2. There was no marked difference in the blood-plasma content of non-protein nitrogen, vitamin A and carotene at 6 months, as between twins on a normal (N) and low (L) plane of nutrition, although the L-twins were growing and maturing more slowly. However, the blood-plasma content of glucose and of most of the free amino acids, was slightly reduced as a result of underfeeding. 3. When at the age of 6 months two twin-pairs were castrated and injected with either testosterone or androstenedione (50 mg every 3rd day, for 2 months), the L-twins of both pairs and the N-twin of one pair grew at a faster rate. Moreover, the concentration of nitrogen in blood plasma increased, the rise being particularly evident in the content of indispensable amino acids. This effect, however, was more pronounced in the N- than in the L-twins. 4. Testosterone treatment enhanced libido in the N-twin but not in the corresponding L-twin. Androstenedione had no effect on libido in either the N-twin or the L-twin. Thus, although testosterone and androstenedione both effectively promoted growth and nitrogen metabolism, androstenedione, unlike testosterone, was devoid of androgenic activity.

SUMMARY The inhibitory effect of underfeeding on the process of male pubescence was studied in three pairs of bovine identical twin calves by feeding one twin on a normal and the other on a low plane of nutrition. As a result of malnutrition the development of the androgenic function of the testes was retarded much more markedly than spermatogenesis. In the undernourished twin the testes contained and secreted less testosterone, and showed a lower testosterone: androstenedione ratio, than in the control animal. This nutritionally conditioned androgen deficiency was clearly reflected in a markedly retarded onset of production of fructose and citric acid by the seminal vesicles. After castration the underfed twin responded to testosterone injections much more sluggishly than the control twin, as shown by the delayed appearance of fructose and citric acid in electrically-induced ejaculates. Observations were also made on the effects of orchitis and cryptorchidism. Both these conditions lowered markedly the androgenic activity in the calves.