Effect of Age on the Lysine and Sulfur Amino Acid Requirement of Growing Chickens

Abstract

Several 14-day growth assays were conducted to determine the dietary lysine and sulfur amino acid (SAA) requirement of the chick during the periods 14 to 28 days and 41 to 56 days posthatching. A sesame meal-gelatin diet supplemented with essential amino acids but limiting in both lysine and SAA and containing 3200 kcal. M.E./kg. was fed at 23% and 20% protein during the 14- to 28-day and 42- to 56-day periods, respectively. The lysine requirement for maximal growth rate was found to be a constant (4.62) percent of the protein with increasing age. The SAA requirement expressed as a percent of the protein, however, decreased from 3.05 ± 0.07% during the third and fourth week to 2.56 ± 0.15% during the seventh and eighth week of the chick’s life.