抄録
Two experiments were conducted to determine whether the excess essential amino acids in low protein diets affects the performance, nitrogen excretion and abdominal fat deposition of broiler chicks. Essential amino acids were classified into seven groups, (1)branched-chain amino acid (BCAA ; leucine+isoleucine+valine) (2)hydroxy amino acid (Thr ; threonine) (3)sulfur-containing amino acid (Met ; methionine) (4)aromatic amino acid (AAA ; phenylalanine+Tyrosine) (5)basic amino acid (BAA ; lysine+arginine) (6)glycine (Gly) (7)tryptophan (Trp) and were supplemented to low crude protein (19% CP) diet at the level of 150% (Experiment 1) and 200% (Experiment 2) of the Japanese Feeding Standard requirement. Seven amino acids supplemented diets, low CP and control (21% CP) diets were fed to 7-day-old chicks for 14 days. Body weight gain of the chicks fed the low CP and amino acids supplemented diets were did not differ among the treatments. Significant reduction in feed intake compared to the control diet were not seen in excess amino acids supplemented diets. Low CP and amino acids supplemented diets significantly increased abdominal fat weight than the control diet in experiment 1, however in experiment 2, compared to the control diet, abdominal fat weight were significantly higher in chicks fed the Gly and Trp supplemented diet among the groups. Nitrogen excreted were not reduced in chicks fed the low CP diets. These results show that the supplementation of excess amino acids to the low CP diet had little effect on abdominal fat deposition of broiler chicks in 1 to 3 wks of age.
