Sexual behaviour of White Leghorn cocks bearing basal hypothalamic lesions in various locations

Abstract

The sexual behaviour of W. Leghorn cocks bearing basal hypothalamic electrolytic lesions in various locations was studied. Lesions located in the mammillary nuclei resulted in functionally castrated cocks (FC), with completely atrophied combs and testes; this seems to indicate a complete block of FRF and LRF secretion. Those birds did not show any sexual activity and were attacked and defeated by the hens. When the lesions were located in the posterior part of the mammillary nuclei, the cocks became partially functionally castrated carrying atrophied testis and large combs (FCLC). In the latter category of cocks the LRF secretion was not affected severely; these birds also did not show any signs of sexual behaviour, but were not defeated by the hens. Treatment of the FC cocks with daily injections of 1 mg/kg b/wt testosterone propionate resulted in a significant increase of their comb size and hematocrit values and they were not attacked by the hens, but did not restore their sexual behaviour. It is suggested that the hypothalamic mammillary nuclei are directly involved in the mechanism controlling sexual behaviour activities of the male domestic fowl.