Development of a Basal Diet to Study Broiler Chicken Responses to the Sulfur-Containing Amino Acids and Sodium Sulfate

Three experiments were conducted to develop a basal diet limiting in the sulfur-containing amino acids and with adequate sodium. Twelve hundred commercial male broiler chicks were grown to 3 weeks of age in battery brooders. Chicks were fed a diet of a corn-soybean meal-poultry oil containing .38% methionine, .74% total sulfur-containing amino acids, and .10% sodium. The first two experiments, pooled for statistical analyses, showed that supplementation with .25% L-methionine significantly increased chick growth over the basal (496 vs. 465 g; P = .034) as did sodium supplementation (518 vs. 465 g; P less than .001). The best growth rate occurred when L-methionine and sodium chloride (NaCl) were supplemented together at .25 and .33%, respectively (579 g gained). The response from NaCl was demonstrated to be due to the sodium and not the chlorine by comparison to responses from potassium chloride (KCl) and sodium carbonate (Na2CO3) supplementation. It is suggested that two "first-limiting" nutrients, methionine and sodium, exist for chicks fed this particular diet. In Experiment 3, a response surface was determined with supplemental sodium (as NaCl) and L-methionine each varying from 0 to .20% (.10 to .30% total sodium and .38 to .58% total methionine). It was concluded that .20% total sodium is adequate to maximize growth and feed efficiency (.20% better than .13%, no different from .27%). Similarly, .17% supplemental methionine (.55% total) appears to be adequate (.17% better than .10%; .20% not better than .17%) with no supplemental choline.