| The development of broilers has been extremely rapid in recent years.And chicken is currently one of the main meat products in the consumer market.Nowadays,the nutritional value of protein,especially animal-derived protein,is increasingly recognized by people.Consumers are eager to get more and better protein from poultry products.In recent years,many research showed the regulation of protein metabolism through nutrient pathways.It was reported that as an important substance involved in the metabolism of one carbon,folic acid is closely related to the process of protein metabolism.This study started with the amino acid,which was the raw material for protein synthes.And with intervention of folic acid in broilers and amino acid targeted metabolomics,this study aimed to explore the mechanism of folic acid regulating protein metabolism,which also provided a theoretical basis for the rational and effective application of folic acid in broiler diet.Experiment 1: Study on the effect of folic acid on amino acid metabolism in broilers based on amino acid targeted metabolomicsWith the aid of amino acid targeted metabolomics technology,this experiment aimed to explore the relationship between folic acid and the amino acid metabolism in breast muscle of AA broiler.In this experiment,105 AA broilers were selected and randomly divided into 3treatment groups(n = 7),namely the control group,the saline group and the folic acid group.All three groups were fed corn-soybean diet with a folic acid level of 1.3 mg/kg.The folic acid group was given folic acid ten times the normal folic acid intake,and the normal saline group was given the same amount of normal saline.After rearing,the serum samples were collected for serum biochemical characteristics analysis.And the breast muscle samples were collected for the detection of amino acid targeted metabolomics and gene expression.The results showed;(1)When compared with the NS groups,folic acid perfusion significantly increased the content of glutamine,serine and proline in breast muscle(P < 0.05).The gene expression of GLUL in breast muscle in FA group also increased(P < 0.05).But no significant difference was found in the gene expression of PSPH,SLC1A5 and GSL(P >0.05).(2)When compared with control group and NS group,folic acid perfusion significantly decreased ALT level and increased ALB level in serum(P < 0.05).(3)No significant difference was found in the IGF1 level in serum and IGF1 gene expression in breast muscle(P>0.05).In conclusion,folic acid mainly affected the endogenous synthesis process of amino acids by regulating the transamination process of amino acids,thereby affecting protein metabolism.And folic acid did not affect the exogenous intake of amino acids in breast muscle.Experiment 2: Effect of folate acid on growth performance and protein metabolism in broilersIn experiment 1,we found that folic acid perfusion affected the amino acid transamination process of broiler breast muscle and the amino acid metabolism.This study aimed to explore the effect of folic acid on protein metabolism in broilers.In this experiment,196 AA broilers were selected and randomly divided into control group and high-dose folic acid group(n = 14).The two groups were respectively fed corn-soybean diet with folic acid levels of 1.3 mg/kg and 13 mg/kg.At 21 d and 42 d,broilers were sacrificed to collect breast muscle,leg muscle,abdominal fat and duodenum and jejunum mucosa.Then the samples were used to detected items of muscle protein metabolism and gene expression of intestinal folate transporter.The results showed that:(1)when compared with the control group,folic acid significantly increased the body weight of broilers on 21 d and 42 d,the ADG and ADFI in the early,late and full periods(P < 0.05).In addition,folic acid also significantly decreased the FCR from 1 to 21d(P < 0.05).(2)when compared with the control group,folic acid significantly increased the breast muscle weight and leg muscle weight of broilers on 21 d and 42d(P < 0.05).In addition,folic acid also increased the breast muscle rate of broilers on 42d(P < 0.05).But no significant difference was found on the leg muscle rate of broilers(P>0.05).What’s more,compared with the control group,folic acid significantly reduced the abdominal fat rate of broilers on 21 d and 42d(P < 0.05).(3)Folic acid significantly increased the FR gene expression of duodenum and jejunum at 21d(P < 0.05),and folic acid also increased the FR gene expression of jejunum of broilers at 42d(P < 0.05),In addition,compared with the control group,folic acid significantly reduced the PCFT gene expression in the jejunum of broilers 42 days(P < 0.05).In conclusion,folic acid could increase the rate of breast and leg muscles,reduce the rate of abdominal fat and improve the production performance of broilers.Experiment 3: Study on the mechanism of folate acid regulating protein metabolism in broilersThe results of experiment 1 and experiment 2 suggested that folic acid affected the protein metabolism in the breast muscle by regulating the amino acid transamination process.This experiment aimed to explore the mechanism of folic acid regulating the protein metabolism of broiler breast muscle.At the end of the second experiment,breast muscle samples were collected to determine the gene and protein expression of AKT/m TOR pathway related factors and myogenic determinant family.The results showed that:(1)When compared with the NS groups,folic acid increased the gene expression of GLUL in breast muscle(P < 0.05).But no significant difference was found in the gene expression of SLC1A5(P>0.05).(2)Folic acid significantly increased the protein expression of phosphorylated AKT and S6K1 in the breast muscle of broilers at 21 d and 42d(P < 0.05).In addition,folic acid also reduced the protein expression of phosphorylated S6 in breast muscle of broiler at 42d(P < 0.05).(3)Folic acid significantly increased Myog gene expression in breast muscle of broilers on 21 d and 42d(P < 0.05).In conclusion,at first,the results proved the conclusion in experiment 1.What’s more,folic acid could activate the AKT/m TOR pathway,thereby increasing the activity of its downstream signal molecule phosphorylation of S6K1,which in turn could increase the gene expression of the myogenic determinant family to complete the regulation of protein metabolism.This study showed that high-dose folic acid have a good effect on broiler performance and muscle protein deposition,which was partly because folic acid could regulate the amino acid transamination process to provide sufficient raw material for protein synthesis.In addition,folic acid could activate the AKT/m TOR pathway to increase the activity of its downstream signal molecules phosphorylating S6K1,which in turn affected the expression of myogenic determinants family,and ultimately affected the protein metabolism process. |
