Dietary Pyrroloquinoline Quinone Addition Alleviated Weaning Stress via Modulation of Gut Microbiota and Metabolic Profiles in Weaned Piglets

Weaning stress in piglets severely restricts swine production efficiency due to growth retardation, immune suppression, and intestinal dysfunction. This study investigated the effects of dietary pyrroloquinoline quinone (PQQ) on 36 weaned piglets (22 ± 1 days old) allocated to six groups (0, 1, 2, 4, 8 and 16 mg/kg PQQ) for 28 days. Results showed that 4-8 mg/kg PQQ improved average daily gain and feed conversion ratio (<i>p</i> < 0.05), enhanced serum immunoglobulin (IgA, IgG) and antioxidant enzyme (T-AOC, SOD, GSH-Px) levels, and reduced inflammatory cytokines (TNF-α, IL-1β, IL-6) (<i>p</i> < 0.05). PQQ modulated gut microbiota, increasing <i>Lactobacillus</i> and <i>Bifidobacterium</i>, and elevated short-chain fatty acid production (<i>p</i> < 0.05). Metabolomic analysis revealed upregulated tricarboxylic acid (TCA) cycle intermediates (citric acid, isocitric acid and malic acid), indicating improved mitochondrial function (<i>p</i> < 0.05). Overall, 4 mg/kg PQQ optimally alleviates weaning stress by enhancing immunity, gut health, and energy metabolism, offering a promising strategy for piglet nutrition.