J. G. Halpin

Effect of Biotin on Reproduction in the Domestic Fowl

Summary Evidence is presented to show that biotin is essential for normal embryonic development in the hens egg. A satisfactory synthetic ration for use in studies of the vitamin requirements of laying and breeding hens is also presented.

Effect of Lactobacillus casei Eluate Fraction on Reproduction in the Domestic Fowl

Summary Evidence is presented to show that the Lactobacillus casei c eluate fraction is essential for normal development of the chicken embryo.

Relation Between Induced Hyperthyroidism and an Unidentified Chick Growth Factor.

Summary A thyrotoxic condition in the chick, induced by feeding desiccated thyroid or iodinated casein was effectively counteracted either by supplementing the diet with condensed fish solubles or by the injection of reticulogen. An increased growth response was obtained upon the addition of either desiccated thyroid or iodinated casein to a ration containing adequate amounts of the known and unidentified chick growth factors. The addition of either 0.125% desiccated thyroid or 0.02 to .03% iodinated casein to the basal ration resulted in an improved assay range for the unidentified chick growth factor (s) in condensed fish solubles and reticu-logen.