Gastrointestinal Microbial Diversity And Volatile Fatty Acid Production In Pigs Fed Different Fibrous Diets With Or Without Cell Wall-degrading Enzyme Supplementation

The microbial diversity and volatile fatty acid(VFA)production in pigs fed different fibrous diets with or without cell wall-degrading enzyme(phytase 1500 U/kg,cellulase 1000 U/kg and xylanase 5000 U/kg diet)supplementation were compared using the Illumina MiSeq sequencing and terminal restriction fragment length polymorphism(T-RFLP)analysis technique.Eight growing castrated pigs fitted with a T-shaped cannula at the terminal ileum were randomly assigned to four diets in each batch,i.e.,batch 1 included wheat bran-based diet(WB),enzyme-supplemented WB,soybean hull-based diet(SH),and enzyme-supplemented SH;batch 2 included broccoli residues-based diet(BR),enzyme-supplemented BR,rice bran-based diet(RB),and enzyme-supplemented RB,according to 4 × 4 Latin square design,respectively.The diets,ileal digesta and feces were collected after 15 days of adaptation in each period.Expt.1.Gastrointestinal microbial diversity and volatile fatty acid production in pigs fed different fibrous diets(WB and SH)with or without cell wall-degrading enzyme supplementationThe microbial diversity and VFA production in pigs fed different fibrous diets(WB and SH)with or without cell wall-degrading enzyme supplementation were compared using the Illumina MiSeq sequencing technique.The results showed as follows:the microbial diversity in the ileal digesta and feces of pigs fed WB or SH had no significant variation,respectively,whereas adding exogenous cell wall-degrading enzyme significantly increased the microbial diversity in the ileal digesta of pigs in each group(P<0.01),and that in the feces of pigs in each group had a tendency to increase(P<0.10).The WB diet increased(P<0.05)the abundances of Lactobacillus,Veillonella and Ruminococcaceae,whereas the SH diet increased(P<0.05)the abundances of Streptococcaceae,Peptostreptococcaceae,Lachnospiraceae,Treponema and Methanobrevibacter.Adding exogenous cell wall-degrading enzyme selectively altered the relative abundances of bacteria in both dietary groups,such as Streptococcus,Enterococcus,Veillonella and Treponema.The SH diet promoted(P<0.01)the concentrations of acetate,propionate and total VFA in the ileal digesta and feces,and enzyme supplementation led to similar results for VFA production(P<0.01)but not for acetate in the feces.Expt.2.Gastrointestinal microbial diversity and volatile fatty acid production in pigs fed different fibrous diets(BR and RB)with or without cell wall-degrading enzyme supplementationThe microbial diversity and VFA production in pigs fed different fibrous diets(BR and RB)with or without cell wall-degrading enzyme supplementation were compared using the Illumina MiSeq sequencing technique.The results showed as follows:the microbial diversity in the ileal digesta of pigs fed BR was significantly higher than that of pigs fed RB(P<0.05),and adding exogenous cell wall-degrading enzyme significantly increased the microbial diversity in the gastrointestinal tract of pigs in each group(P<0.05).The BR diet increased the abundances of Ruminococcus,Bacteroides,Lachnospira and Peptostreptococcus(P<0.05),whereas the RB diet increased the abundances of Lactobacillus and Eubacterium.Adding exogenous cell wall-degrading enzyme significantly influenced the abundances of Lactobacillus,Veillonella,Megasphaera,Lachnospira,Prevotella,Eubacterium and Ruminococcus.The BR diet promoted(P<0.05)the concentrations of total VFA in the feces,and enzyme supplementation led to similar results for VFA production(P<0.05).Expt.3.Comparative analysis of gastrointestinal microbial diversity in pigs fed different fibrous diets(BR and RB)with or without cell wall-degrading enzyme supplementation by T-RFLP and Illumina MiSeq sequencingThe microbial diversity in pigs fed different fibrous diets(BR and RB)with or without cell wall-degrading enzyme supplementation were compared using the T-RFLP and Illumina MiSeq sequencing technique.We analyzed microbial diversity,composition and abundances by 16S rRNA gene-based T-RFLP and Illumina MiSeq sequencing to compare the accuracy and reproducibility of the two techniques on gastrointestinal microbial communities in pigs.The results showed as follows:the effects of fiber source and enzyme supplementation on the gastrointestinal microbial diversity in pigs detected by two techniques were consistent on the general trend.The microbial diversity and richness detected by Illumina MiSeq sequencing were significantly higher than the results from T-RFLP.The Illumina MiSeq sequencing provided more comprehensive and accurate fingerprints of gastrointestinal microbial community structure than T-RFLP,whereas T-RFLP only can represent a few numerically dominant phylotypes with apparent overestimation of their relative abundance in the gastrointestinal tract of pigs.