The effect of exogenous testosterone on homospermic and heterospermic fertility in the cock.
Cocks were administered testosterone (T) for 14 days via 0, 1, 2, or 4 Silastic capsules implanted subcutaneously. Each capsule released 1.04 mg of T per day. Concentrations of T in plasma and the proportion of eggs fertilized from homospermic insemination of hens were determined. Concentrations of T in plasma were variable and unaffected by treatment. The proportion of eggs that were fertilized by cocks decreased during treatment with 1 capsule, increased over the experiment in the group with 2 capsules, and increased after treatment ended in the group with 4 capsules. In heterospermic tests, cocks with distinguishable offspring were paired and semen was mixed within pairs. One cock in each pair received either 1 or 4 Silastic capsules containing T for 14 days; the other cock in the pair received none. The proportion of chicks sired by cocks treated with 1 capsule remained unchanged throughout the experiment, whereas the proportion sired by cocks treated with 4 capsules decreased markedly during the recovery period. The response to T was apparently dependent upon dosage and the sensitivity of the cock to T. The concentration of T in the plasma of the cock had little relationship to fertility. These results indicate that heterospermic insemination can be used as a sensitive method to detect the subtle effects of hormonal treatment.
D000818:Animals; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D005298:Fertility / Q000187:drug effects*; D005306:Fertilization; D008297:Male; D013094:Spermatozoa / Q000502:physiology*; D013739:Testosterone / Q000008:administration & dosage / Q000494:pharmacology*
D013739:Testosterone