| This study was conducted to investigate the effects of different dietary arginine levels on growth performance,serum biochemical indexes and intestinal function of Linwu ducks aged 8～35 days.A total of 560 7-day-old Linwu ducks were randomly divided into 5 groups with 7replicates per group and 16 ducks per replicate according to a single factor design.They were fed diets with the arginine levels of 0.9%(GroupⅠ),1.0%(GroupⅡ),1.1%(GroupⅢ),1.2%(GroupⅣ)and 1.3%(GroupⅤ),respectively.The experiment lasted for 28 days.The growth performance,serum biochemical indexes,intestinal development and microbial flora indexes of Linwu ducks were determined,and the optimal dietary arginine level of Linwu ducks aged 8～35 days was determined,which provided the basis for the formulation of feeding standard and dietary preparation of Linwu ducks.The results of the study are as following:1.Different levels of arginine have little effect on the average daily weight gain and average daily feed intake of Linwu ducks(P>0.05),and the effect on the feed-to-weight ratio of Linwu ducks is extremely significant(P<0.01).The feed-to-weight ratio was highest in groupⅠand lowest in groupⅢ.GroupⅠwas significantly higher than groupⅢ(P<0.01),groupⅣ(P<0.01)and groupⅤ(P<0.05).The difference between the other groups was not significant(P>0.05).The quadratic regression model between feed-to-weight ratio(Y)and arginine level(X)was established as Y=31429X~2-721.43X+6.594,and the optimal level of arginine was calculated to be1.148%.2.The effects of different arginine levels on serum GLU,BUN,UA,TG,Tch,HDL-C,LDL-C and AST of Linwu ducks were not significant(P>0.05),but the effects on the activities of ALP and ALT were significant(P<0.01);and the effects on MDA,SOD,GSH-PX,T-AOC,TP,ALB,GLB,A/G and Ig A were not significant(P>0.05),but the effects on Ig G(P<0.01),Ig M and NO(P<0.05)were significant.The concentrations of Ig G and Ig M in groupⅠwere significantly higher than those in other groups(P<0.05).The concentrations of NO in groupⅠwas 20.67%(P>0.05),31.21%(P<0.05),41.42%(P<0.05),30.93%(P<0.05)lower than that of groupⅡ,Ⅲ,ⅣandⅤ,respectively.The quadratic regression model between serum NO(Y)and arginine level(X)was established as Y=-581429X~2+13909X-70.046,and the optimal level of arginine was calculated to be 1.196%.3.The effects of different arginine levels on the length,relative length,CD and V/C of the duodenum,jejunum and ileum of Linwu ducks were not significant(P>0.05),but the effects on the weight,VH of the duodenum,jejunum were significant(P<0.05),and the effects on ileum were not significant(P<0.05).The VH and CD of the duodenum were the highest in groupⅤ.4.The number of OTU shared by the intestinal flora was 3069,and the number of OTU uniquely in group I,II,III,IV and V were 1263,237,224,349 and 180,respectively.The core flora were Bacteroidetes,Firmicutes and Proteobacteria.At the genus level,the dominant bacteria were Bacteroides,Alipipes and Rikenellaceae＿RC9＿gut＿group.The difference of Alpha diversity index and Beta diversity index were not significant(P>0.05).In conclusion,the optimal dietary arginine level of Linwu ducks aged 8～35 days is 1.148%～1.196%. |
