Assessment of the Availability of Amino Acids in Fish Meal, Soybean Meal and Feather Meal by Chick Growth Assay

AN earlier report described a chick growth assay for the determination of the availability of amino acids in intact proteins (Smith and Scott, 1965a). The assay involved the use of a crystalline amino acid basal diet. Graded levels of the test amino acids in the basal provided a standard reponse curve against which was compared the growth of chicks fed a similar diet in which intact protein served as the source of the test amino acid. Calculations were based upon the relationship between dietary level of the test amino acid and growth response. It now appears that the amount of the test amino acid consumed rather than the dietary level may be a more valid basis of calculation (Campbell, 1966). In addition a mixture of crystalline amino acids simulating those present in the intact protein was added to the basal diet. This addition apparently led to an overestimation of the . . .