THE occurrence of a pigmentation failure resulting in a white bar in the flight feathers of poults fed rations containing low levels of protein and/or fiber has been observed frequently (Goff, 1932 and Grau et al. 1946). Fritz et al., (1946) and German et al., (1949) showed that the feather pigmentation could be inhibited in poults fed adequate total protein by feeding vegetable protein concentrates which are low in lysine. Crystalline lysine was effective in preventing the abnormality. This problem has been studied further to determine whether amino acids other than lysine are involved and to obtain more information on the relation of lysine and total protein level to the pigmentation failure.EXPERIMENTALRations and experimental conditionsSix experiments were conducted in which various combinations of protein concentrates and amino acids were fed. The basal ration consisted of the following per 100 grams: wheat bran, 10.0 g.; ground barley, 5.0 .