Composition and nutritional role of gut microbiota on growth performance of pigs at different growth stages

This study has investigated the relationship between the gut microbiota composition and the growth performance in pigs from birth to the finishing stage, focusing on nutrient metabolism. Of fifty-nine crossbred pigs [(Landrace × Large Yorkshire) × Duroc] from seven sows, individuals with high and low daily gain (DG) were assigned to high DG (HDG, n 11) and low DG (LDG, n 8) groups. Faecal samples collected at weaning (21 d), growing (95-106 d) and finishing (136-152 d) stages were analysed for amino acids, SCFA and microbial composition using 16S rRNA sequencing. Although birth and weaning weights were similar in both groups, the HDG group had significantly higher weights in the growing and finishing stages (P < 0·01). The microbial composition of the LDG group revealed a higher abundance of f_Lachnospiraceae;__ at weaning (P < 0·05), whereas the HDG group contained a higher abundance of g_Streptococcus and g_Prevotella 7 at the finishing stage (P < 0·05). Functional analysis revealed increased amino acid metabolism in the HDG group at the finishing stage (P < 0·05). During the growing stage, total free faecal amino acid content was low in the HDG group (P < 0·05); at weaning, levels of isobutyric and isovaleric acids, key amino acid fermentation products (P < 0·05, P < 0·01), were higher. These findings indicate growth stage-specific differences in the gut microbiota and metabolic profiles between groups with different growth performance, suggesting that microbial and metabolic characteristics may influence growth performance.