Effects Of Dietary Acidolysis Products Of Oxidized Konjac Glucomannan On Intestinal Digestive Enzyme?Intestinal Microflora And Intestinal Mucosal Immunity Of Schizothorax Prenanti

The effects of dietary acidolysis products of oxidized konjac glucomannan on growth performance, digestive ability, number of partial intestinal microflora,diversity of intestinal microflora and expression of intestinal mucosal immune-related genes-mhc2, tcr, casp-9 of Schizothorax prenanti were studied to provide the basis for the popularization and application of LOKGM as functional additives. A total of three hundred and sixty healthy fishes with average body weight of 81±2.64g were randomly divided into 4 groups with 3 replicates and 30 fishes per replicate. The 4 groups were control group (basal diet), LOKGM-0.8% group (basal diet+0.8% LOKGM), LOKGM-1.6% group (basal diet+1.6% LOKGM), LOKGM-3.2% group (basal diet+3.2% LOKGM), respectively. The experiment lasted for 75 d (15 d for adaptation and 60 d for test). After feeding, the weight gain rate (WGR), special growth rate (SGR), intestinal length index, intestinal body index; intestinal protease, lipase, amylase activity; the number of Aeromonas hydrophila, Bacillus, Lactobacillus and E. coli in the intestinal was quantified by real-time quantitative PCR. Diversity of posterior gut microflora was determined based on V3 variable regions of bacteria 16S rDNA by using denaturing gradient gel electrophoresis (DGGE) technique. Expression of mhc2, tcr and caspase-9 mRNA in-intestinal mucosa were evaluated by real-time PCR of Schizothorax prenanti. The results showed as follows:(1) The effects of LOKGM on growth performance:compared with the control group, the SGR and WGR were significantly increased in the LOKGM-0.8% group (P<0.05), while no effects were seen in LOKGM-1.6% and LOKGM-3.2%groups (P>0.05).(2) The effects of LOKGM on relevant indicators of digestion:compared with the control group, the intestinal length index and intestinal body index of Schizothorax prenanti were not affected in LOKGM-0.8% group (P>0.05), the intestinal length index was significantly reduced (P<0.05)and the intestinal body index was significantly increased (P<0.05)in LOKGM-1.6% group, the intestinal length index was not affected and the intestinal body index was significantly reduced (P<0.05) in LOKGM-3.2% group; compared with the control group, protease activity in anterior intestine and lipase activity in middle and posterior intestine were significantly increased (P<0.05) in LOKGM-0.8% group, while lipase activity in anterior intestine was significantly decreased (P<0.05); protease activity in anterior and middle intestine and lipase activity in anterior and posterior intestine were significantly increased (P<0.05) in LOKGM-1.6% group, while lipase activity in middle intestine was significantly decreased (P<0.05); protease activity in anterior and middle intestine and lipase activity in middle and posterior intestine were significantly increased (P<0.05) in LOKGM-3.2% group, while lipase activity in anterior intestine was significantly decreased (P<0.05); amylase activity was decreased in all groups supplemented with LOKGM (P<0.05).(3) The effects of LOKGM on the number of partial intestinal microflora:compared with the control group, the number of Aeromonas hydrophila in anterior and middle intestine and E.coli in anterior?middle and posterior intestine of Schizothorax prenanti were significantly decreased in the LOKGM-0.8% group (P<0.05), also the number of Bacillus in anterior intestine and Lactobacillus in posterior intestine were significantly increased (P<0.05); the number of Aeromonas hydrophila in anterior middle and posterior intestine and E.coli in middle and posterior intestine were all significantly decreased in LOKGM-1.6% group (P<0.05) and the number of Bacillus in posterior intestine and Lactobacillus in anterior and posterior intestine were significantly increased (P<0.05); the number of Aeromonas hydrophila in anterior intestine and E.coli in middle and posterior intestine were significantly decreased (P<0.05) in LOKGM-3.2% group, besides, the number of Bacillus in anterior intestine and Lactobacillus in middle intestine were significantly increased (P<0.05).(4) The effects of LOKGM on diversity of posterior intestinal microflora:compared with the control group, the diversity of posterior intestinal microflora was significantly increased in the LOKGM-1.6% and LOKGM-3.2% group (P<0.05), but the diversity of posterior intestinal microflora was not affected in the LOKGM-0.8% group (P>0.05).(5) The effects of LOKGM on expression of intestinal mucosal immune-related genes-mhc2, tcr and casp-9:compared with the control group, the expression level of mhc2, tcr mRNA were all significantly down-regulated in LOKGM groups (P<0.05); the expression level of casp-9 was not affected by LOKGM(P>0.05).Above all, dietary acidolysis products of oxidized konjac glucomannan can promote the growth performance of Schizothorax prenanti, mainly by improving intestinal digestive enzyme activity, optimizing the structure of intestinal microflora, thereby promoting the digestion and absorption of nutrients, improving immunity, keeping the fish healthy. The optimal dietary LOKGM level for optimum growth performance and immunity of Schizothorax prenanti was suggested to be 0.8%.