Physiological Differences Associated with Genetic Differences in Egg Production

THE pituitary gonadotrophic hormones, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are generally believed to control ovulation and egg production (Sturkie, 1965). Other hormones and biological substances are known o t influence egg production but their effects are generally considered to be through effects on general body metabolism. It is then likely that a genetic increase in egg production achieved through selection may involve either an increase in the secretion of the gonadotrophic hormones and/or an increase in target organ sensitivity to them. The object of this experiment was to determine whether gonadotrophin sensitivity, as measured by male chick response to gonadotrophin, had increased in two lines of poultry selected for increased egg production as compared to their base population. MATERIALS AND METHODS S275 and S% are two lines of White Leghorns selected for increased egg production and OCS is their base population. These lines and their development, production characteristics…