Compound probiotic fermentation promotes feed utilization in weaned piglets via biosynthesis and metabolism of amino acid

Abstract Probiotics represent a promising alternative to antibiotics in livestock production. This study investigated the effects of compound probiotic fermentation (FAM, comprising Lactobacillus acidophilus and Bacillus subtilis ) on nitrogen utilization and nutrient digestibility in weaned piglets. A total of 180 piglets (28 days old; initial weight: 8.21 ± 0.67 kg) were allocated to three groups: control (basal diet), FAM (basal diet + 0.1% FAM), and antibiotic (basal diet + 55 mg/kg kitasamycin + 75 mg/kg chlortetracycline). After a 30-day trial, FAM supplementation significantly increased apparent nutrient digestibility of crude protein and ether extract, enhanced duodenal and jejunal digestive enzyme activities, and reduced fecal nitrogen excretion and serum urea nitrogen levels ( p < 0.05). Serum metabolomics revealed that FAM upregulated metabolites linked to energy metabolism (e.g., creatine, L-carnosine), which are metabolites of amino acid metabolism, and enriched pathways such as amino acid biosynthesis and protein digestion. These findings demonstrate that FAM improves nitrogen utilization efficiency and gut health in piglets via biosynthesis and metabolism of amino acids, offering a viable alternative to antibiotics.