Effects Of Dietary Supplementation Of Isoleucine On Performance,Health Status And Meat Quality Of AA Broiler Chickens

The purpose of this study was to investigate the effects of different levels of isoleucine（Ile）on the performance,healthy status and meat quality of AA broiler chickens.A total of24,000 1 d heathy AA broiler chickens were randomly divided into three treatments with eight replicates per treatment and 1000 broilers per replicate.The control（CON）was fed a basal diet,and the treatments were respectively fed a basal diet supplemented with 400 mg/kg（ILE400）and 800 mg/kg（ILE800）Ile.The test period was 42 d.The day of test beginning and the ending,the body weight,feed intake and dead amoy number of broilers was recorded.On day 42 d,one broiler chicken with body weight close to that of the treatment were slaughtered for sampling in each replicate,and the samples of blood,liver,breast muscle,leg muscle and cecal chyme were collected.The results were as follows:（1）Compared with the CON,the 42 d body weight and 0-42 d average daily gain of broiler chickens in the ILE400 treatment were remarkably increased（P<0.05）;the feed to gain ratio in the ILE400 and ILE800 treatments were significantly decreased and the survival rate was significantly increased in the ILE400 and ILE800 treatments（P<0.05）;The carcass rate and pectoral muscle rate of broiler chickens at 42 d in the ILE400 and ILE800 treatments were significantly increased,and the abdominal fat percentage significantly decreased（P<0.05）.（2）Compared with the CON,the serum UREA,GLU and TCHO concentrations of broiler chickens in the ILE400 and ILE800 treatments were significantly decreased（P<0.05）;The activity of GSH-PX in serum of ILE400 treatment was significantly increased（P<0.05）,and the concentrations of TNF-αwere significantly decreased（P<0.05）.Serum TNF-αconcentrations were significantly decreased and IL-10 concentrations were significantly increased in ILE800treatment（P<0.05）;The m RNA relative expressions of FASN and SREBP1c in liver were significantly down-regulated in the ILE400 treatment（P<0.05）,and the relative m RNA expressions of ATGL,LPL,HSL and Sirt1 in liver were significantly up-regulated（P<0.05）.（3）Cecal microbe high-throughput sequencing results showed that at the phylum levels,the relative abundance of Proteobacteria,Cyanobacteria,unidentified＿Bacteria and Acidobacteriota in the ILE800 treatment was significantly increased with the CON（P<0.05）,yet the relative abundance of Firmicutes,Bacteroides and Desulfobacterota was significantly reduced（P<0.05）.At the genus level,the relative abundance of Dyella,unidentified＿Chloroplas and Terriglobus in ILE800 treatment were significantly increased compared with the CON（P<0.05）,yet the relative abundance of Barnesiella,Alistipes,Bacteroides,Butyricicoccus,Colidextribacter,Butyricimonas,Bilophila,Lachnoclostridium,[Ruminococcus]＿torques＿group,UCG-005 and NK4A214＿group were remarkably decreased（P<0.05）.The Shannon index was significantly increased in ILE400 treatment（P<0.05）,and Simpson index was notably decreased in ILE800 treatment compared with the CON（P<0.05）.In addition,PCo A cluster analysis and ANOSIM analysis showed that the microbial community composition of the ILE800 treatment was significantly different from that of the CON and the ILE400 treatments.（4）Spearman correlation analysis showed that Lachnoclostridium was significantly positively correlated with GLU（P<0.05）;Barnesiella was significantly positively correlated with ALB,UREA and GLU（P<0.05）;NK4A214 was significantly positively correlated with ALB（P<0.05）;UCG-005 was significantly positively correlated with ALB and LDL（P<0.05）;Terriglobus was significantly negatively with GLU（P<0.05）;Butyricicoccus was significantly positively correlated with LDL and ALB（P<0.05）;Butyricimonas was significantly positively correlated with ALB,UREA and GLU（P<0.05）;Alistipes was significantly positively correlated with ALB and UREA（P<0.05）;Bilophila was significantly positively correlated with ALB,UREA,GLU,TCHO and IL-6（P<0.05）;Dyella was negatively correlated with ALB and GLU（P<0.05）.（5）Compared with the CON,L*and a*values in pectoral muscles and leg muscles at the ILE400 treatment were significantly increased（P<0.05）;The content of crude protein in leg muscle of the ILE800 treatment were significantly increased,and the b^*value in pectoral muscles were significantly decreased（P<0.05）.These above results indicate that dietary supplementation of 400 mg/kg Ile could improve performance,antioxidant capacity and immune performance of broiler chickens,promote lipolysis and inhibit lipid synthesis in the liver,as well as have an improving effect on the health condition of broiler chickens under the present experimental conditions.It has a certain improvement effect on meat color,but no significant effect on other meat quality indicators.Dietary supplementation of 800 mg/kg Ile increased the abundance of pathogenic bacteria in cecum of broilers,while decreased the abundance of beneficial bacteria,suggesting that dietary supplementation of 800 mg/kg Ile has negative effects on intestinal health.Comprehensively considering the performance,the health status and the raw material costs,the best production benefit were could obtained by adding 400 mg/Ile in the diet under the conditions of this experiment.