Further Studies on the Influence of Aureomycin in the Chick Diet upon Subsequent Reproductive Performance of Laying Hens

SIZEMORE, Lillie, Denton and Bird (1953) reported the effect of a vitamin B12-antibiotic feed supplement to the chick diet upon the subsequent reproductive performance of Rhode Island Red pullets. When a vitamin B12 deficient breeder diet was fed, the hatchability of fertile eggs produced by pullets reared on antibiotic-supplemented diets was greater than that of fertile eggs produced by pullets reared without an antibiotic. In some cases the hatchability differences persisted throughout the first laying year of the experiment. To determine the duration of persistence of the hatchability differences, the experiment was carried through the second laying year and the results are presented in this paper. EXPERIMENTAL PROCEDURE The experimental procedure was the same during the second year as during the first year. Two cockerels per pen were substituted for the old males. The hens that were carried over into the second year had received as growing diets the Connecticut …