The Role of Proline and Certain Non-Essential Amino Acids in Chick Nutrition

Abstract

THE relative abundance of serine, alanine, aspartic acid and proline in natural proteins has made it difficult to determine their role in chick nutrition when diets containing intact proteins are employed. The dispensable nature of these amino acids in a crystalline amino acid diet was reported by Almquist and Grau (1944). The omission of serine, alanine and aspartic acid from their amino acid mixture had no effect on chick growth. When proline was omitted, the chicks failed to grow for about four days, but after that time they grew at the “normal rate.” It was concluded that the initial lag in growth rate was due to a period of adaptation required to allow establishment of adequate synthesis mechanisms for proline from other amino acids furnished in the diet. Since the omission of proline had no lasting effect, it was also classified as a dispensable amino acid. Klain (1959) used a …