The Nutritional Value of the Individual Nonessential Amino Acid as the Nitrogen Source in the Chick Nutrition

The nutritional values of nonessential amino acids as the nitrogen source in the crystalline amino acid diet for the chick growth were examined. The nitrogen of the nonessential amino acids in the basal diet for chick was substituted for a nonessential amino acid to be tested on the nitrogen base. The experimental methods were the same as in the evaluation of the nutritional value of d-amino acids previously reported. Nonessential amino acids were classified into four groups.

1. Very useful nitrogen source: Glutamic acid, Aspartic acid

2. Useful nitrogen source: Alanine, Diammonium citrate

3. Insufficient nitrogen source: Glycine, Proline

4. Harmful for chick growth: Serine

At the end of experiment chicks were killed and the concentration of free amino acids in the serum were measured. The concentration of glycine and serine in the serum increased when glycine was tested, but that of serine in the serum only increased when serine was tested. This result suggested the pathway from glycine to serine was fast and the opposite one was very slow.