Gut Microbiota Related to Fiber Digestibility were Identified by Variation of Apparent Fiber Digestibility in Chinese Suhuai pig

Abstract Background: Dietary fiber plays an important role in porcine gut health and welfare. Fiber mainly degraded by the gut microbiota, whereas most gut microbiota related to fiber digestibility of pigs are still unidentified. To reveal gut microbiota associated with apparent digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF), apparent NDF, ADF digestibility of 274 Suhuai female finishing pigs at the age of 160 days were measured. The gut microbiota of Suhuai pigs were analyzed through 16S rRNA gene sequencing, respectively. Results: Large phenotypic variations in apparent NDF and ADF digestibility were separately found among Suhuai pigs. The coefficient of variation of NDF and ADF digestibility was 12.08% and 18.08%, respectively. The mean values of digestibility of H-NDF and H-ADF groups were 30.20% and 33.76% more than those of the L-NDF and L-ADF groups (P＜0.01), respectively. A total of 927 and 935 operational taxonomic units (OTUs) were confirmed from two types of fecal samples,respectively. There were14 phyla in all samples and the abundances of Spirochaetae, Bacteroidetes and unclassified_k__norank were significantly different between H-NDF and L-NDF groups (P＜0.05) and the abundances of Spirochaetae, Verrucomicrobia, unclassified_k__norank and Fibrobactere were significantly different between H-ADF and L-ADF group (P＜0.05).A total of 188, 183, 188 and 185 genera were separately identified in H-NDF, L-NDF, H-ADF and L-ADF groups, while 6, 1, 5 and 2 genera were separately specific to H-NDF, L-NDF, H-ADF and L-ADF groups. The microbiota of H-NDF and H-ADF clustered separately from the microbiota of the L-NDF and L-ADF along principal coordinate 1, respectively. Compared with L-NDF group, 29 genera were found to be potential biomarkers in H-NDF group. Compared with L-ADF group, 23 genera were found to be potential biomarkers in H-ADF group. The most important functions and metabolic pathways of the above potential biomarkers included carbohydrate transport and metabolism. Conclusions: Microbial community structures were significantly different between high and low fiber digestibility groups. Twenty nine and 23 genera were found to be potential biomarkers in H-NDF and H-ADF group, respectively. The biomarkers may be the key functional microbiota related to apparent fiber digestibility.