Studies on gonadal steroids in relation to maturation in the Japanese Quail

Abstract

Plasma levels of testosterone (T), oestradiol-17ß (E2-17ß) and progesterone (P) were studied using immuno-assays in relation to age, sexual maturity and to Vitamin D3 metabolism of male and female Japanese Quail. Quail raised on 8L:16D (SD) remained sexually immature while quail on 16L:8D (LD), 24LL or d70TLD became sexually mature. Female birds came into lay around d45 or around the 29th long day in quail transferred from SD to LD at d70 (d70TLD). Plasma steroid levels were dependent on the sexual maturity with lowest levels found in sexually immature quail. Once the time of egg-laying had been reached plasma E2-17ß and P levels were higher in females than in males while T levels were higher in males. In quail bled sequentially during sexual maturation plasma P and E2-17ß levels in females rose prior to the onset of lay. T levels in male quail started to rise at the time of rapid testicular development. The steroid levels observed help to explain the changes in Vitamin D3 metabolism seen with sexual maturation and the differences between the sexes.

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