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

The Essential Nature of Glycine and Proline for Growing Chickens

“…Almquist and Grau (1944) classified proline as a dietary dispensable amino acid for growing chickens since they were unable to demonstrate a growth depression upon deleting it from a crystalline amino acid diet. Later work with improved purified diets (Klain et al, 1959;Greene et al, 1962;Sugahara and Ariyoshi, 1967) led to the conclusion, however, that proline was indeed a dietary essential for the growing chick. Roy and Bird (1959) even suggested that practicaltype diets would respond to supplemental proline.…”

The Development of an Amino Acid Reference Diet for the Early Growth of Chicks

“…(Klain et al, 1960a). It was further demonstrated by Greene et al (1962) that chicks fed this improved amino acid mixture required dietary proline for maximum growth and that this requirement could not be met by other members of the group of so-called non-essential amino acids. This finding was in contrast to earlier results with the poorer mixture since Klain et al (1960b) had been unable to demonstrate a dietary requirement for glycine.…”

Avian Physiology

“…The function of taste in nutrition is an enigma. However, the preference behavior of laboratory animals is not a reliable guide to the nutritional adequacy of a diet (Kare and Scott, 1962). A similarly correct nutritional choice was not made when the sugar was replaced with an isocaloric solution of fat or protein.…”