Glycine-Serine Requirement for Chicks

The requirement of glycine or serine was established for optimum growth in chicks. Equimolar quantities of serine completely replaced glycine for maximum chick gains. Chicks fed a chick starter diet for the first five days had a requirement of 0.25% glycine for optimum weight gain for the feeding period of 6-15 days. Chicks fed experimental diets from one day of age required a minimum level of glycine between 0.50 and 1.0%. The 1.40% level of serine did not produce results which were significantly different than those obtained with lower levels of glycine or serine. There was no significant difference in weight gain of chicks fed various proportions of glycine for days 6–10 if the chick diets were supplemented with glycine from 1–5 days inclusive. The possibility exists that glycine is needed in high amounts in early growth for uric acid formation, purine synthesis and metabolic regulation.