Lactobacillus -fermented feed alters growth performance, fecal short-chain fatty acid contents, metagenomics, and metabolomics in growing pigs

This study sought to comprehensively evaluate the impact of Lactobacillus -fermented feed produced with Latilactobacillus curvatus SQ13 on the growth and fecal short-chain fatty acid (SCFA) contents, as well as metagenomic and metabolomic parameters, in growing pigs. One hundred crossbred pigs were randomized into two dietary treatment groups. Animals were given either a basal diet (CON) or a diet containing Lactobacillus -fermented feed (LP) over a 32-day period. The LP group exhibited a significantly reduced feed conversion ratio (FCR) and lower fecal valeric acid concentration compared with the CON group ( P < 0.05). Microbial community analysis revealed that the relative abundance levels of Candidatus_Eremiobacterota , Cyanobacteriota , Lacrimispora , and Candidatus_Onthomorpha were markedly increased in the LP group ( P < 0.05), whereas Actinomycetota , Pseudomonadota, Solobacterium , and Mitsuokella were significantly decreased ( P < 0.05). KEGG pathway analyses indicated that arachidonic acid metabolism, phototransduction—fly, and Th17 cell differentiation were the three most significantly altered pathways. Correlation analysis further demonstrated that FCR was positively associated with Solobacterium abundance and downregulated metabolites, while showing negative correlations with Alistipes and upregulated metabolites. Collectively, these findings suggest that Lactobacillus -fermented feed improves growth efficiency and modulates valeric acid levels in growing pigs, likely through coordinated alterations in gut microbial composition and host metabolic processes. These results offer a potential foundation for the application of fermented feed in swine production systems. IMPORTANCE Our study demonstrated that fermented feed produced by Latilactobacillus curvatus ZLA031 could improve growth efficiency, decrease valeric acid levels in growing pigs, likely through coordinated alterations in fecal microbiota composition, and host metabolic processes. Our work provided both experimental evidence and a theoretical framework supporting the application of Lactobacillus -fermented feed in swine production, while highlighting the need for further mechanistic research.