Effects of Growth Stage and Rearing Pattern on Pig Gut Microbiota

Understanding the developmental period or the patterns of gut microbiota is important for nutritionists when designing a feed formula or adjusting a feeding strategy. The effects of growth stage or rearing pattern on pig gut microbiota have not been fully investigated. Herein, 39 fecal samples from pigs aged 3-9 months under two rearing patterns were collected to analyze the gut microbiome. Samples were clustered into three distinct groups, namely, early (3 months), middle (5 months), and late (7 and 9 months) stages, using principal coordinate analysis and analysis of similarities test. The rearing-pattern effects were very minimal, and no differences were observed in the alpha diversity [observed operational taxonomic units (OTUs) and Shannon index] of gut microbiota. From early and middle to late stage, Shannon index gradually decreased and OTUs gradually increased. Pigs at early stage were enriched with bacteria from family Prevotellaceae, including the genera Prevotella_9 and Prevotellaceae_NK3B31, whereas pigs at late stage were enriched with family Ruminococcaceae, including genera Ruminococcaceae_UCG-005 and Oscillospira. Pigs in the semi-free-grazing farm group were significantly enriched with bacteria from order Clostridiales. Growth stage better explained the changes in porcine gut microbiota than rearing patterns.