G. F. Combs

Effect of Zinc Deficiency in Hens on Hatchability and Embryonic Development.

Summary Evidence is presented indicating that deficiency of zinc in the diet of breeding hen, results in (1) lowered hatchability (2) gross embryonic anomalies characterized by impaired skeletal development and (3) varying degrees of weakness in chicks which hatch.

Impaired Antibody Production in Chicks Fed Diets Low in Vitamin A, Pantothenic Acid or Riboflavin.∗:

Summary Chicks fed diets partially deficient in either Vit. A, pantothenic acid or riboflavin showed significantly lower agglutinin response to S. pullorum antigen as compared with controls. The weight of bursa, in relation to body weight, was less in chicks fed the vitamin-low diets, being significantly lower than that of controls only for the chicks fed the vitamin A-low diet. No significant differences were observed in thymus, spleen or adrenal weights. The results indicated that the dietary need for these nutrients is appreciably greater for optimum antibody production than the levels required for rapid growth.

Action of vitamin B12 in counteracting glycine toxicity in the chick.

Summary Vitamin B12-deficient chicks were fed vitamin B12-deficient basal diets supplemented with 0, 1 and 4% glycine in combination with 0, 3, and 30 μg of vitamin B12 (supplied by Mercks APF Supplement No. 3) per kilogram. The growth of the chicks that received either 1 or 4% added glycine in the vitamin B12-deficient basal diets was depressed. Those chicks which received 4% added glycine without vitamin B12 suffered excessive mortality. The addition of as little as 3 micrograms of vitamin B12 per kilo of diet overcame the inhibitory action of both levels of glycine. These results indicate that vitamin B12 functions in the metabolism of glycine.

Effect of Orally Administered Penicillin-Resistant Microorganisms on Growth of Chicks.

Summary Pure cultures of E. coli and A. aerogenes were grown, lyophilized, and fed to chicks as dietary supplements both in the presence and in the absence of procaine penicillin G. Little or no chick growth response was obtained when either of these organisms were added to the ration in the absence of the antibiotic. Greater gains were obtained when 10 ppm procaine penicillin G were fed. When viable cultures of A. aerogenes and E. coli were fed in combination with penicillin, growth was further increased significantly. The effectiveness of the antibiotic in promoting chick growth was increased 64 and 80% when these organisms were added to the feed. The results obtained illustrate the influence of bacterial environment on the antibiotic growth effect and in nutritional studies.

Effect of Yolk Removal in Day-old Chicks on Early Nutritional Requirements.∗

Summary An operative technic for the removal of the yolk from day-old chicks has been described. This procedure was developed to render chicks relatively free of the nutrients transmitted through the yolk from the dam. Observations on the growth rate of deutectomized chicks as compared with that of unoperated controls show that the operation had little or no effect on growth when an adequately supplemented diet was supplied. The results of these trials demonstrate that vit. B12 or a substance possessing vit. B12 activity was present in the yolk of the day-old chick and that it was removed by deutectomy.