Effect of Protein Level on the Lysine Requirement of the Chick

Abstract

Various levels of sesame meal protein and lysine have been fed to young chicks, and the effects on growth and feed consumption have been observed. It was found that as the protein level was increased, the lysine requirement for maximum growth at a particular protein level increased. This was true whether the lysine requirement was expressed as percentage of the diet, or as the weight of lysine consumed per day per unit of body weight. Amino acid requirements may best be expressed in terms of percentages of the diet at a particular protein level, preferably the minimum protein level necessary to promote rapid growth. While higher levels of sesame protein provide higher levels of lysine, this additional lysine is inefficiently used, because the requirement for it is also increased. Other amino acids are also inefficiently used, because the protein level is above the optimum. A lysine bioassay procedure in which the amino acid content of proteinaceous material is determined by addition to a sesame meal diet will produce erroneous results unless corrections are made for the increased lysine requirement with increased protein levels.