Thyroprotein-Feeding to 7-Year-Old Hens

Abstract

IN 1942, groups of two-year-old White Leghorn hens were started upon an experiment to determine the long-time effect of the continuous feeding of synthetic thyroprotein. Progress reports of our observations have been made (Turner et al. 1945a, b; 1946a, b; 1947, and 1948). The present report concerns the egg production records of the surviving hens during the seventh laying year, and the fifth continuous year on thyroprotein for many of the hens.EXPERIMENTAL METHODSThe reader is referred to the previous paper for details of the management and feeding of these chickens (Turner and Kempster, 1948). The experimental hens received the same battery ration as the controls except that 10 gm. thyroprotein** was mixed into each 100 pounds of feed. The present experimental year started on October 17, 1947 and closed October 16, 1948.In the examination of Table 1, it should be pointed out that all of the hens during .