Relationship of Rate of Thyroxine Secretion to Rate of Egg Production in the Domestic Fowl

Abstract

IT has long been recognized that the activity of the thyroid gland is concerned in egg production, but the extent to which its activity affected production has not been reported. A number of earlier workers attempted to alter egg production by changing thyroid activity. Some of these investigators used desiccated thyroid; later workers have used iodinated casein. Most of the workers were unable to increase egg production with desiccated thyroid.Turner and his associates (1945a) and (1946) found that the feeding of 10 grams of iodinated casein per 100 pounds of feed to hens 2 to 5 years of age increased egg production. This increase in production was primarily in the late spring and summer months when production normally declines. Turner suggests that the normal decline in egg production in late spring and summer and with age is due to a drop in thyroxine secretion. Turner et al. (1945b) also .