Requirement of Sulfur Amino Acids for Meat-type Chicks

Abstract

Thirteen experiments were conducted to study age difference in the requirement of sulfur amino acids for 2 meat-type chicks, i.e. White Cornish × White Plymouth Rock and White Cornish × New Hampshire, and a egg-type chicks, i.e. White Leghorn. Graded Levels of DL-methionine were added to corn-soy or cornstarch-soy basal diets, of which cystine and methionine levels were adjusted based on the determination of these amino acids by an amino acid analyzer. Requirement of sulfer amino acids were estimated based on body weight gain and feed efficiency of the chicks.Requirement of sufur amino acids for chicks younger than 3 weeks of age was confirmed to be 0.66% in the diet containing 20% of crude protein, while that for chicks older than 4 weeks was 0.57% in the diet containing 16% of crude drotein. No difference in the requirement among the breeds tested was observed.It was confirmed that after 4 weeks of age, dietary sulfur amino acids could be reduced to such a level, on which growth rate of younger chicks was retarded. When adequate sulfur amino acids level was shown as per cent of dietary crude protein, that was 3.3 and 3.6 per cent of crude protein, for younger and older chicks than 4 weeks of age, respectively.