Live Multi-Strain Probiotics Enhance Growth Performance by Regulating Intestinal Morphology and Microbiome Population in Weaning Piglets

The effects of different forms of multi-strain probiotics on weaning piglets are limitedly addressed. Thus, this study investigated the effects of live or inanimate multi-strain probiotics comprising <i>Lactobacillus plantarum</i>, <i>Streptococcus thermophilus</i>, and <i>Bacillus subtilis</i> on growth performance, intestinal morphology, fecal microbiota, short-chain fatty acids, and intestinal gene expression of weaning piglets. A total of 160 weaning piglets (4 weeks old) were randomly allocated into four treatments (CON: basal diet; AB: basal diet with 110 ppm and 66 ppm colistin in the weaning and nursery phases, respectively; LP: basal diet with 2.0 × 10⁹ CFU/kg live probiotics; and IP: basal diet with 2.0 × 10⁹ CFU/kg inanimate probiotics). Piglets fed with LP had significantly lower FCR compared to those of the CON and IP groups in week 4 to week 8 (<i>p</i> < 0.05). Moreover, the LP group had significantly higher villus height (VH) compared with AB at week 6, lower crypt depth (CD) compared with IP, and higher VH/CD ratio compared to other treatments at week 10 (<i>p</i> < 0.05), which indicate healthier intestinal morphology. Probiotic treatments (LP and IP) increased <i>Bifidobacterium</i> population compared to CON at week 6 and lowered <i>Enterobacteriaceae</i> at week 6 and week 10 (<i>p</i> < 0.05). Regarding gene expressions of intestinal integrity, LP showed significantly higher TFF3 expression compared with CON and AB at week 6 and compared with other treatments in jejunum at week 10 (<i>p</i> < 0.05). IP treatment had significantly higher MUC2 expression compared to other treatments at week 6 and week 10 (<i>p</i> < 0.05). Overall, live multi-strain probiotics improved growth efficiency by enhancing gut integrity and microbiome balance, making them a potential antibiotic alternative to ameliorate weaning stress and promote productive performance in weaning piglets.