Fungal community in the feces of grazing Tibetan pigs, captive Tibetan pigs, and commercial pigs and its interaction with dietary fiber digestion

Abstract:

[Objective] This study aimed to investigate the differences in the structure of fungal community in the feces of grazing Tibetan pigs, captive Tibetan pigs, and commercial pigs[Duroc×Landrace×Yorkshire (DLY) pigs, aged 5 months] in the Tibet Plateau and to obtain the fungi associated with the digestion of dietary crude fiber.[Methods] The apparent digestibility of dietary crude fiber of grazing Tibetan pigs, captive Tibetan pigs, and DLY pigs was determined via digestion experiments. The full-length ITS region of fecal fungi was determined by single molecule real-time sequencing technology to analyze the structure and diversity of fungal community. The Pearson correlation analysis was performed between apparent digestibility of dietary crude fiber and fungal community.[Results] A total of 58 fungal species belonging to 4 phyla, 13 classes, 23 orders, 39 families, and 55 genera were identified. At each taxonomic level, the fungal taxa in the feces of grazing Tibetan pigs were more than those of either captive Tibetan pigs or DLY pigs (P<0.05). Ascomycota and Basidiomycota were the dominant phyla, and the fungal abundance at the phylum level had no significant difference among the

grazing Tibetan pigs, captive Tibetan pigs, and DLY pigs (P ≥ 0.05). At the levels of class, order,

family, genus, and species, the fungal abundance of grazing Tibetan pigs was significantly higher than that of either captive Tibetan pigs or DLY pigs (P<0.05). The grazing Tibetan pigs had the most diverse fungi with unique operational taxonomic units (P<0.05). The principal coordinate analysis revealed that grazing Tibetan pigs had different fecal fungi compared with captive Tibetan pigs and DLY pigs (P<0.05). The grazing Tibetan pigs had higher apparent digestibility of dietary crude fiber than captive Tibetan pigs and DLY pigs (P<0.05). Pearson correlation analysis showed that Phialemonium atrogriseum, Phialemonium inflatum, and Podospora communis had a positive correlation with the apparent digestibility of dietary crude fiber (P<0.05).[Conclusion] The grazing Tibetan pigs had stronger fiber digestibility than the captive Tibetan pigs and DLY pigs. In the future, we could identify more fungal groups from their gut. This information would be helpful in studying the excellent characteristics of Tibetan pigs, such as their tolerance to roughage.

Key words:Tibetan pigs;commercial pigs;fungal community;fiber digestion;correlation analysis