Effect Of Arginine Family On Growth Performance Lipid Metabolismand Transcriptional Expression Level Of Some Genes Related To Meat Quality In Broilers

One-day old male broilers were used in a six-week period feeding trail to investigate the effects of arginine (Arg), glutamime (Glu) and aspartic acid (Asp) supplementations on the growth performance, lipid metabolism and the transcriptional expression of some genes related to meat quality. Corn-soybean meal diet was used as the basal diet. The results showed:1. The present study indicated that the weight gain was not affected when Glu or Asp was added separately (P>0.05). However, the combination of Glu and Asp significantly increased the weight gain (P<0.05), but had no effect on the feed conversion ratio (P> 0.05). The abdomen fat ratio was reduced (P<0.05) when Glu or Asp was added separately. However, the combination these two amino acids increased the abdomen fat ratio, which was consistent with the previous studies. The supplementation of Glu significantly increased the thickness of subcutaneous fat and eviscerated percentage (P< 0.05). The greater width of intermuscular fat in the groups of Asp and the mixture compared to the control (P<0.05) demonstrated that the performance and carcass traits of the broilers were improved by the supplementations of Asp and Asp+Glu. The present study indicated that the weight gain was not affected when Glu or Asp was added separately (P>0.05). However, the combination of Glu and Asp significantly increased the weight gain (P<0.05), but had no effect on the feed conversion ratio (P> 0.05). The abdomen fat ratio was reduced (P<0.05) when Glu or Asp was added separately. However, the combination these two amino acids increased the abdomen fat ratio, which was consistent with the previous studies. The supplementation of Glu significantly increased the thickness of subcutaneous fat and eviscerated percentage (P< 0.05). The greater width of intermuscular fat in the groups of Asp and the mixture compared to the control (P<0.05) demonstrated that the performance and carcass traits of the broilers were improved by the supplementations of Asp and Asp+Glu. Height and thickness of intestinal villi were increase, whereas the crypt depth was decreased by Glu supplementation. The length of duodenum, jejunum and ileum and the length index were increased by either Glu or Asp supplementation, whilst the relative weight index of the duodenum and jejunum were increased by either Glu or Arg supplementation.2. Fatty acid composition of the meat showed that the supplementation of Arg significantly increased the ratio of n-6 poly-unsaturated fatty acids (PUFA) to n-3 PUFA (n-6/n-3) in the breast muscle (P< 0.05), however, decreased n-6/n-3 in the leg muscle (P< 0.05). Supplementation of Arg +Glu and Arg+Glu+Asp increased n-6/n-3 in both the breast and the leg muscle compared to control (P< 0.05). Supplementation of Asp or Glu+Asp decreased n-6/n-3 in the breast and leg muscle (P< 0.05). Concentrations of n-9 mono-unsaturated fatty acid (MUFA) in the breast muscle were increased only by Arg supplementation, whilst their concentrations in both the breast and leg muscle were decreased by the other treatments (P< 0.05). TG levels in the serum was significantly reduced (P<0.05) by adding Glu and Asp separately, and the effect of Glu was greater than Asp, but the effect of their combination was not (P> 0.05), indicating the blood triglyceride level could be decreased by these two amino acids. TC level in the blood was increased (P<0.05) by the supplementation of Glu and Asp; the similar effect was observed these two acids were added separately, however, not statistically significant (P> 0.05). Compared with the control, the concentration of HDL-C was decreased by the three treatments, in which Glu supplementation had a significant effect (P< 0.05).3. The expression of mRNA of ACC, FAS, CPT-1, LPL, PPARa gene measured by RT-PCR showed that, compared to the control, the expression of PPARa gene in the liver was significantly reduced (P<0.05) by the supplementations of Glu, Asp and their mixture, whereas no significant difference was observed among the three treatments (P>0.05). The effect of amino acid supplementation on the expression of PPARa gene in the lipid tissue was contrary to that in the liver. Expression of ACC gene in the live was reduced by the supplementation of Glu or Asp, whilst which in the lipid tissue was also reduced by the supplementation of Glu, Asp and their mixture. FAS gene expression in the liver was significantly decreased by the addition of Glu, Asp and their mixture (P<0.05), but no significant difference was observed among these three treatments (P>0.05). FAS gene expression in the lipid tissue was reduced (P< 0.05) by the mixtures of Arg+ Glu, Arg+ Asp and Glu+ Asp. The expression of ACC gene in the lipid tissue was higher (P< 0.05) than in the liver, however, which was slight different to that of FAS. The expression of CPT-1 gene was significantly lower (P<0.05) in the liver when Glu, Asp and their mixture was added, with the most significant effect was observed in the Glu group, demonstrating the inhibition of the CPT-1 gene expression in the liver by Glu and Asp. The expression CPT-1 gene in the lipid tissue was increased (P< 0.05) by the mixture of Glu and Asp. The expression of LPL gene in the liver was not affected by the mixture of Glu and Asp (P>0.05), however, which was increased by the Glu. The expression LPL in the lipid was reduce (P< 0.05) by the mixture of Glu and Asp. The expressions of LPL and CPT genes in the lipid tissue were significantly higher than in the liver (P<0.05).4. Analysis of the levels of the blood hormone showed that the liver MDA content was reduced significantly, while the activities of SOD, CAT and GH were increased by the addition of amino acids. The hormone secretion of AA broiler was promoted effectively when Arg or Glu was added alone, which could lasted until 42 days of age. The addition of Asp alone increased the GH level until to 21 days of age. However, this effect was not significant in the late stage (42 d) and showed a downward trend. Addition of the mixture of these amino acids resulted in a decreased in the level of GH. The insulin level was lowered in the earlier stage, however, increased during the later stage when Asp was added alone, which showed a downward trend throughout the growth stage when Arg and Glu were added alone or mixed. The combination of these three amino acids resulted in a lower insulin level in the earlier stage, whereas a greater level in the later stage. The levels of T4 were increased significantly when Arg, Glu and Asp was supplemented separately, which was more significant than the effect of their mixtures.5. The concentrations of the amino acids related to the muscle flavor of the broilers was increased significantly by the dietary supplementation of the amino acids of the arginine family. The formation of inosine and inosinic acid in muscle of the broilers were promoted directly or indirectly by either the single or mixed supplementations of these amino acids. In addition, the mRNA expression of FABP was also improved by this approach.