The optimum dietary essential amino acid pattern for male Taiwan country chicks

Abstract

The objective of this study was to estimate the optimum dietary essential amino acid pattern for male Taiwan country chicks. A series of experiments was conducted with chicks, 14 d of age, for 2 wks. A basal synthetic diet was established using a dose response test for all essential amino acids referring to the broiler requirements recommended by NRC (1994). Twelve chicks were sacrificed at the beginning to provide initial body nitrogen data, and every group of six birds received the basal diet or a diet with a deficiency in a single essential amino acid in twenty one treatments by intubation according to their daily metabolic body weight (MBW). Deposited body nitrogen was determined using comparative slaughtering. According to the daily intake from the limiting amino acid per unit of MBW and the body nitrogen accretion rates for every two deficient groups with the same limiting amino acid but at different levels, a corresponding straight line was computed for each essential amino acid to intersect with a horizontal line made by the body nitrogen accretion rate of the control group. The x coordinate of the intersection represented the daily requirement for growth plus maintenance based on MBW corresponding to the essential amino acid. The amino acid ratios can be considered as the optimum pattern of dietary essential amino acids. The results, expressed with respect to lysine = 100, were arginine 105, methionine 81, histidine 34, tryptophan 18, leucine 103, phenylalanine 135, isoleucine 69, threonine 65 and valine 79. This pattern could be utilized to compute the dietary requirements (g/kg feed) for all essential amino acids by multiplying by the requirement of a single essential amino acid cited from the literature.