Riboflavin supp. (500 mcg./g.)

MACHLIN (19S4) reported that a re-duction of dietary protein or trypto-phan eleven days after administration of methionine-S35 to laying hens resulted in a relative increase in sulfur35 deposition in the egg albumen. This increase in deposi-tion of sulfur35 due to an amino acid de-ficiency suggested a possible procedure for estimating dietary amino acid requirements of the laying hen. Fisher and Johnson (1956) reported the development of a syn-thetic diet containing free amino acids in-stead of protein that maintained egg pro-duction for a 30-day experimental period. Since the cost of conducting research with synthetic diets of this type limits the dura-tion of the experimental periods, an assay procedure whereby amino acid deficiencies could be detected in a short period of time would be valuable for determining dietary amino acid requirements. The following studies using a lysine de-ficient laying diet were designed to ascer-tain if the results obtained by the proce-dure described by Machlin (1954) with short-term trials would be similar to the results of a long-term trial conducted under the same experimental conditions