Characterizing the hypothalamic-pituitary-gonadal axis in turkeys genetically selected for increased egg production

Abstract

Within the United States, the turkey industry has historically focused on increased meat production. Studies have shown that there is a negative correlation between meat and egg production. Previous research in our laboratory compared high egg producing hens (HEPH) to low egg producing hens (LEPH). It was found that HEPH express increased levels of mRNA for genes associated with stimulating the hypothalamic-pituitary-gonadal (HPG) axis. We also demonstrated that the hypothalamic-pituitary-thyroid (HPT) axis exerts some effect on egg production. In order to increase our understanding of differences in egg production, we focused on a genetically selected line with increased egg production (E line) and a random bred control line (RBC1). Related to the HPG axis, differences were found related to steroidogenesis and feedback mechanisms. Within the HPT axis, the RBC1 line tended to have increased mRNA levels of genes associated with stimulation of the axis compared to E line.