Modification of lead toxicity and organ distribution by dietary sulfur amino acids in chicks (Gallus domesticus).

Chicks (Gallus domesticus) were fed a basal diet deficient in methionine and total sulfur amino acids with 0 or 1000 ppm added lead for 21 days. Methionine or methionine and cystine addition improved growth regardless of dietary lead level. Cystine addition alone improved growth only when lead was present. Relative inhibition of growth by lead was greater with diets containing no added methionine. Hepatic non-protein sulfhydryl concentration was increased by lead and all amino acid additions. Organ lead concentrations were generally lower with added amino acids. Dietary methionine appears to counteract lead toxicity more effectively than cystine.