Further Observations on the Utilization of Homocystine, Choline and Related Compounds by Chicks

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Abstract
A study was made of the responses of vitamin B12-deficient chicks to homocystine, betaine, choline, methionine, vitamin B12 and folic acid as measured by early growth on diets which were deficient in several respects. A “factorial” design of adding the supplements enabled their interrelationships to be measured. The response to homocystine was markedly increased by vitamin B12 under a variety of dietary conditions. However, in the absence of vitamin B12 homocystine often actually depressed growth. The response to homocystine in the presence of added vitamin B12 was increased by the addition of choline or betaine. However, when vitamin B12 was not added, the response to homocystine plus choline or betaine added as a mixture was no greater than the sum of the responses to homocystine and choline or betaine when tested individually. Choline appeared to be highly effective as a “methylating” agent for homocystine in the presence of vitamin B12 on a diet which was markedly deficient in methionine. There was no indication that the amino acids in the basal diet could effectively replace choline for this purpose. The incidence of perosis on a purified diet without added dimethylaminoethanol was high when vitamin B12 was added and choline was omitted. The incidence was not reduced by adding betaine.