Feeding Thyroprotein and Sex Hormones to Laying Hens

Abstract

A SERIES of reports from this laboratory on the feeding of thyroprotein to White Leghorn hens of increasing age has indicated that in the younger birds, the addition of thyroid hormone to the feed was without effect during the fall and winter months but appeared to be responsible for more sustained egg production during the spring and summer (Turner et al. 1947). Production strain Rhode Island Red birds showed a similar seasonal response (Turner et al. 1945). With advancing age, the Leghorns have begun to show a more marked difference in egg production throughout the year.These differences in response to thyroprotein-feeding have been interpreted as indicating that the White Leghorns and Rhode Island Reds included in these experiments have received an inheritance for the secretion of optimum amounts of thyroid hormone under the environmental conditions of the fall and winter. In the spring and summer, with increasing environmental temperature .