The Glycine-Serine Interrelationship in Chick Nutrition

For maximal chick growth glycine is considered an indispensable amino acid (Almquist and Grau, 1944). However, since serine by loss of the β-carbon atom can be converted to glycine (Shemin, 1946), it is conceivable that serine might spare dietary glycine. Thus the nonessentiality of glycine reported recently by Sugahara and Ariyoshi (1967) can perhaps be explained by the presence of a plethora of l-serine in their basal diet. Wixom et al. (1955) demonstrated that serine could partially replace the need for glycine in chicks fed casein protein. The purpose of our work was to evaluate the replacement value of serine for glycine in fast-growing chicks fed a minimal nitrogen, well balanced, crystalline amino acid diet (Table 1). Information regarding selection and care of the chicks has been outlined previously (Dean and Scott, 1965). Previous assays had established that the dietary glycine requirement for maximal growth on the diet used herein . . .