Effects Of α-ketoglutaric Acid On Growth Performance,Nitrogen Metabolism And Gene Expression Of MTOR Signaling Pathway Of Skeletal Muscle In Piglets

This study mainly investigated the effects of low-protein diet supplementation of AKG on the growth performance,nitrogen metabolism,relative expression of amino acid transporter genes,and mTOR signaling pathway in piglets fed diets.Forty-eight piglets with an initial weight of(11.53±0.04)kg were randomly divided into 4 groups.Each group had 4 replicates and each replicate had 3 pigs.The crude protein content of the diets was 14.96%,group A was the control group with no AKG was added;B,C,and D were the experimental groups,and the AKG addition of group B was 0.5%,group C was 1.0%and group D was 1.5%.Synthetic amino acids were added to necessitate the amino acid balance according to standard ileal digestible amino acid requirements.The trial period lasted for 28d.The results showed:1.Compared with group A,group D significantly increased piglet growth performance(P<0.05),and significantly reduced fecal nitrogen and urine nitrogen emissions(P<0.05).The growth performance of the C and D groups and the reduction of fecal nitrogen and urine nitrogen emissions were not significantly(P>0.05).The growth performance and the reduction of fecal nitrogen and urine nitrogen emission in group A and B were significantly different(P<0.05).It shows that 1.0%and 1.5%AKG can both improve piglets’growth performance and reduced nitrogen emissions.The correlation analysis showed that there was a significant positive correlation between the daily gain,nitrogen deposition and AKG addition(P<0.05),and there was a significant negative correlation between nitrogen discharge and AKG addition(P<0.05).2.1.0%and 1.5%AKG can significantly increased serum total protein and glucose(P<0.05),significantly reduced serum urea nitrogen content(P<0.05),promote protein digestion and utilization,and increase amino acid content utilization rate.There was a significant positive correlation between IGF-1 concentration and AKG addition in the serum of piglets(P<0.05),and there was a significant negative correlation between UREA concentration in the serum and the amount of AKG addition(P<0.05).In this study,regression analysis showed that there was a significant positive correlation between the amount of AKG added and IGF-1concentration in piglet serum,and there was a significant negative correlation with the concentration of UREA in the serum.3.1.0%AKG significantly up-regulated the expression of EAAC1 and B~0AT1 in the posterior jejunum of piglets(P<0.05).The expression of amino acid transporters in the three groups of 0.5%,1.0%and 1.5%AKG decreased in the ileum,and 1.5%AKG significantly down-regulated the expression of CAT1 and EAAC1(P<0.05).Through regression analysis,it was found that the amount of AKG addition significantly increased the expression of CAT1,EAAC1,and B~0AT1 in anterior jejunum of piglets(P<0.05),and significanly down-regulated the expression of CAT1,EAAC1,and B~0AT1 in the ileum(P<0.05).4.The expression of S6K was up-regulated at 1.5%AKG,but it was not significantly different from that of group A(P>0.05),but both 1.0%and 1.5%AKG upregulated the expression of mTOR and 4EBP1(P<0.05),increased protein translation,and promoted protein deposition,improved the growth performance of piglet.In this study,the regression analysis revealed that there was no significant positive correlation between 4EBP1 and mTOR expression and AKG addition in the skeletal muscle of piglets,but the expression of 4EBP1 and mTOR had a rising trend(P>0.05).In summary,1.0%and 1.5%AKG have better performance in improving piglet’s growth performance,reducing nitrogen emissions,up-regulating mTOR signaling pathway,increasing protein deposition,and promoting growth of piglets.Through regression analysis,there was a significant positive correlation between daily gain,nitrogen deposition serum IGF-1 content and AKG addition,and there was a significant negative correlation between nitrogen emissions and UREA concentration in piglets serum and AKG addition,in piglets The expression of amino acid transporters CAT1,EAAC1,and B~0AT1 in the anterior jejunum was significantly up-regulated,and the expression of CAT1,EAAC1 and B~0AT1 in the ileum was significantly down-regulated.