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.

Metagenomic Analysis Reveals New Microbiota Related to Fiber Digestion in Pigs

“…At the phylum level, the sum of relative abundance of Firmicutes and Bacteroidetes reached more than 90%, indicating that the microorganisms in Suhuai pig feces are mainly composed of Firmicutes and Bacteroidetes ( Figures 1A,B ). This result is consistent with previous results of 16S rRNA gene sequencing ( Niu et al, 2020 ). Other microorganisms mainly belong to Actinobacteria, Tenericutes, and Proteobacteria.…”

“…There are a large number of microorganisms in animal intestines, and their rich genes can make up for the lack of congenital function of animals, just like an organ of the body. The results show that Firmicutes and Bacteroides are dominant and their sum of relative abundance reached more than 90% in the intestine of Suhuai pigs ( Figure 1 ), which is consistent with the research of Adhikari et al (2019) on PIC genetics nursery pigs and the research of Niu et al (2019 , 2020) on Sutai pigs and Suhuai pigs. Previous studies have found that Firmicutes and Bacteroides were capable of degrading many carbohydrate polymers in different ruminants, including cattle ( Stewart et al, 2018 , 2019 ; Gharechahi et al, 2021 ), camels ( Gharechahi and Salekdeh, 2018 ), and moose ( Svartström et al, 2017 ).…”

“…The data of apparent NDF and ADF digestibility were obtained from our previous research ( Niu et al, 2020 ). In the previous studies, we selected 274 healthy Suhuai female finishing pigs aged 160 days with the same feeding conditions.…”

“…About 0.5 g of samples were taken and the contents of NDF and ADF in diet sample and each pig fecal sample were determined by ANKOM A200 filter bag technique ( Van Soest et al, 1991 ) and the apparent digestibility of each pig was calculated. The following equation was used to calculate the digestibility of 274 sample ( Niu et al, 2020 ):…”

“…In previous studies, we collected the feed and fecal samples of 274 healthy Suhuai female finishing pigs aged 160 days and determined the apparent digestibility of NDF and ADF. We found that the coefficients of variation (CV) of apparent NDF and ADF digestibility of Suhuai pigs was 12.08 and 18.08%, respectively ( Niu et al, 2020 ). To detect the characteristics of gut microbiota and microbial gene functions of pigs with high and low fiber apparent digestibility and to reveal microbiota related to fiber digestion in pigs, samples from Suhuai pigs with extreme high and low apparent NDF digestibility and extreme high and low apparent ADF digestibility were subjected to shotgun metagenomic sequencing in this study.…”