EFFECT OF FASTING AND OF FEEDING A NONPROTEIN DIET ON PLASMA AMINO ACID LEVELS IN CHICK

Feeding a nonprotein-containing diet lowered the concentration of essential amino acids in the blood plasma below the level noted when chicks were fasted over a comparable period of time (3, 6, 12 or 24 hr.). With time, several amino acids (methionine, isoleucine, leucine, tyrosine and phenylalanine) but notably lysine, progressively accumulated in blood plasma under fasting conditions. Threonine was unaffected. Plasma lysine also increased with time when chicks were fed a nonprotein diet; plasma threonine decreased and other amino acids were largely unaffected.