REGULATION OF REPRODUCTION IN TURKEY HENS BY THYROID HORMONES

The goal of this research is to definethyroid axis activity in the context of the preovulatory hormonal surge, linking thyroid axis pertubationsto the low egg production phenotype in turkey hens. Our specific objectives are to: 1) Define the hormonal profiles of the reproductive and thyroid axes in low egg producing turkey hens (LEPH), averageegg producing turkey hens (AEPH), and highegg producing turkey hens (HEPH) during the open period; 2) Determine the influence of circulating thyroid hormone levels on the reproductive axis during peak egg production; and 3) Characterize pituitary responsiveness to thyrotropin-releasing hormone (TRH) stimulation in LEPH and HEPH.