Testosterone aromatization in high and low mating lines of gallinaceous birds

Capons from high (HML) and low (LML) mating lines of Japanese quail and chickens received testosterone propionate, 5α-dihydrotestosterone (5α-DHT) or estradiol benzoate injections after which copulatory behavior was observed during exposure to live females and to a female model. With live females, the testosterone-treated HML capons mated significantly more than the other HML groups. All LML capons mated infrequently and at comparable levels. When tested with the model, estrogen-treated LML capons mated significantly more frequently than testosterone-treated LML capons, suggesting testosterone aromatization rate was affecting mating activity. This possibility was tested with HLM and LML intact cocks and capons receiving silastic implants of either testosterone, 5α-DHT or a combination of estradiol and 5α-DHT (E+DHT). Mating activity of intact HML cocks, T-treated, and E+DHT-treated HML capons were similar, and all groups mated significantly more than the control or 5α-DHT-treated capons. There were no significant differences between any of the LML groups. The data suggested that limited testosterone aromatization was not the cause of relatively reduced sexual activity in the LML males.