four protein sources were used : ( 1 ) egg protein , ( 2 ) protein hydrolysate , ( 3 ) protein hydrolysate diluted with non-essential amino acids , ( 4 ) protein hydrolysate mixed with food proteins ( 'pku protein ' ) , comparable with the diet previously used ( kindt et al . 1983 , 1984 ) .
C0013700
egg protein
C0033684
protein