Inhibitory Effect Of Xylo-oligosaccharide On Swine Pathogenic Bacteria And Its Effects On Growth Performance,Antioxidant Properties And Intestinal Microbial Diversity In Weaned Piglets

Antibiotics have been used widely in animal husbandry production to maintain health,improve production efficiency and increase economic benefits of farmers,but its use also has resulted in lots of problems such as antibiotic resistance,drug residues and food safety.Therefore,it is very necessary to search for alternative to replace antibiotics in animal production.Xylo-oligosaccharide(XOS)is a new type product of oligosaccharide which is considered as a potential alternatives of antibiotics used in the animal production and its antibiotic effect and applied effect have been become the focus of people's attention.The aims of this thesis were to research the inhibitory effect of xylo-oligosaccharide on swine pathogenic bacteria in vitro and its effects on growth performance,antioxidant properties and intestinal microbial diversity in weaned piglets.The experiments were divided into three parts.Experiment 1 Inhibitory effect of xylo-oligosaccharide with different particle size on three kinds of swine pathogenic bacteria in vitro The experiment was conducted to investigate inhibitory effect of xylo-oligosaccharide(XOS)with different particle size(common XOS and super microcrushing XOS)on swine pathogenic Escherichia coli,Staphylococcus aureus and Salmonella typhimurium in vitro.The plate culture method was used to test antibacterial effect and the bacterial growth was determined by tube culture method.The result showed that XOS with different particle size inhibited the proliferation of swine pathogenic Escherichia coli,Staphylococcus aureus and Salmonella typhimurium.The minimum inhibitory concentration(MIC)of common XOS were 20,25 and 17.5 mg·mL-1 respectively,and the MIC of super microcrushing XOS were 20,30 and 20 mg·mL-1 respectively for Swine Escherichia coli.,Staphylococcus aureus and Salmonella typhimurium.The results suggested that XOS had antibacterial effect on three kinds of swine pathogenic bacteria.Experiment 2 Effects of xylo-oligosaccharides on the growth performance,diarrhea rate and serum and liver antioxidant indexes of weaned piglets The study was conducted to investigate the effect of different doses of xylo-oligosaccharides(XOS)on growth performance,diarrhea rate and serum and liver antioxidant indexes in weaned piglets.A total of 72 crossbred piglets(Duroc×Landrace×Large White)weaned at 35 days with initial body weight of 10.14±0.15 kg were randomly assigned into 4 groups with 3 replicates per group and 6 piglets per replicate.Piglets were fed a basal diet(control group),a basal diet plus 100(Exp.I),200(Exp.?)and 400 mg·kg-1 XOS(Exp.?),respectively.The results showed that the basal diets supplemented with 200 or 400 mg·kg-1 XOS decreased significantly feed to gain ratio(P<0.05)compared with the control group.Diarrhea rates were lower(P<0.05)in the added XOS groups than control group in weaned piglets.The diets supplemented with XOS enhanced markedly(P<0.05)the serum T-AOC,liver SOD and CAT activity,however,decreased remarkably MDA contents(P<0.05)of serum and liver.The best dose supplemented with XOS was 200 mg·kg-1 in diet.Experiment 3 Effects of xylo-oligosaccharides on intestinal microbial diversity and volatile fatty acid concentration in weaned piglets The present study was conducted to evaluate the effects of xylo-oligosaccharide on intestinal microbial diversity and volatile fatty acid(VFA)concentration in weaned piglets.The microbial diversity and VFA concentration were analyzed by using the Illumina MiSeq sequencing technique and gas chromatographic technique,respectively.The experimental design was the same experiment.2,and the intestinal microbial diversity was compared between a basal diet and a basal diet plus 400 mg·kg-1 XOS.The results showed as follows:(1)The diets with XOS significantly increased(P<0.05)the Chaol value and the Shannon index of microbial diversity in ileum,caecum and colon.(2)At the phylum lever,compared with a basal diet,the diet supplemented with XOS remarkably increased(P<0.05)the proportion of Bacteroidetes,Actinobacteria,Proteobacteria in ileum,Bacteroidetes and Unclassified in caecum and colon,and significantly decreased(P<0.05)the proportion of Firmicutes in ileum,caecum and colon and Spirochaetae in caecum and colon.(3)At the genus level,diet supplemented with XOS significantly increased(P<0.05)the proportion of Prevotella,Bacillus,Staphylococcus,Lactobacillus,Weissella,Blautia,Faecalibacterium,Eubacterium,Dialister and Halomonas in ileum,Methanobrevibacter,Methanosphaera,Porphyromonadaceae,Prevotella,La.ctobacillus,Oscillospira and Dialister,Megasphaera in caecum,and Parabacteroides,Prevotella,Lactobacillus,Coprococcus,Roseburia,Oscillospira,Dial is ter,Megasphaera and Phascolarctobacterium in colon,however,markedly decreased(P<0.05)the proportion of Pothia,Streptococcus,Clostridium,Actinobacillus,Aggregatibacter,Pasteurella in ileum,Streptococcus,Clostridium,Blautia,SMB53,Sphaerochaeta in caecum,and Methanobrevibacter,Methanosphaera,Streptococcus,Dorea,Ruminococcus,Sphaerochaeta in colon,compared with a basal diet.(4)The diet supplemented with XOS remarkably increased(P<0.05)the concentrations of lactic acid,acetate,propionate,butyrate and total volatile fatty acids in the digesta of ileum,caecum and colon.