Reproductive performance of turkey hens as influenced by hormone implants

Large White turkey hens were implanted with silicone capsules containing either cholesterol (control), progesterone, 17-beta oestradiol (E2), oestrone (E1) or a combination of progesterone and E2. Egg production and fertility were measured. Blood samples were collected weekly for measurement of progesterone by radioimmunoassay. 2. Progesterone alone caused a several-fold increase in serum progesterone concentrations initially and significantly depressed egg production. Simultaneous administration of E2 significantly decreased progesterone concentration, but did not ameliorate the decrease in egg production. 3. There were significant positive correlations between serum progesterone concentration and egg production in control birds and those receiving E2 and E1. There was no significant correlation between progesterone concentration and fertility. 4. The results indicated that, within the physiological range, higher progesterone concentrations are associated with higher egg production. However, maintenance of constant progesterone concentrations throughout the reproductive season by means of implants was not achieved. Implants of E1 and E2 did not affect fecundity.