Abstract
The present study was conducted to determine the effects of glycine (Gly) or glutamic acid (Glu) on growth performance, weights of breast meat and abdominal fat, and various lipid fraction contents in the liver, serum and breast meat of chicks fed a diet supplemented with DL-methionine (Met) plus L-cystine (Cys). The basal diet containing sulfur amino acids (0.64% of diet) was supplemented with Met plus Cys at 1.25% of diet (diet A). The diet A was supplemented with either glycine (diet A+Gly) or glutamic acid (diet A+Glu) at 5g/kg diet. Body weight and breast meat weight were significantly heavier in chicks fed the diet A+Gly than those fed the basal diet. Chicks fed the diet A+Glu increased feed efficiency compared with those fed the basal diet and diet A. The feed intake was significantly lower for chicks fed the diet A+Glu than for those fed the diet A+Gly. The addition of Met+Cys to the basal diet resulted in decrease in abdominal fat weight. Moreover, abdominal fat weight was lower in chicks fed the diet A+Glu than those fed the diet A alone. Met+Cys (diet A) results in the reduction of triglyceride contents in the liver and breast meat compared to the basal diet. Gly (diet A+Gly) could decrease the liver triglyceride content, while Glu (diet A+Glu) gave rise to an increase in it in comparison to the basal diet or the diet A. However, phospholipid content in the serum and breast meat of chicks fed Glu (diet A+Glu) was significantly lower than those fed Gly (diet A+Gly).
