Factors affecting efficacy of methionine hydroxy analogue for chicks fed practical diets.

The relative values of the calcium salt of the hydroxy analogue of methionine (MHA) and L-methionine were studied in chick feeding tests with five practical type diets deficient in the sulfur amino acids. Performance was improved with the addition of either substance to each of the five diets. Methionine was slightly more effective at low levels of addition to the four diets primarily deficient in methionine. The two supplements were equally effective in one diet based on corn, soybean, and meat and bone meals, a diet with a wider methionine/cystine ratio. Both the practical and highly purified amino acid diets thus showed similar differences in efficacy of the two products as the methionine/cystine ratio of the diet changed. Methionine also was more effective than MHA in overcoming the deleterious effects produced by the addition of ethionine to a practical type diet.