Microencapsulated sodium butyrate (MS-SB) is an effective sodium butyrate additive which can reduce the release of sodium butyrate (SB) in the fore gastrointestinal tract. In this study, we assess the protective effects and mechanisms of MS-SB in Clostridium perfringens (C. perfringens)-challenged broilers. Broiler chickens were pre-treated with SB or MS-SB for 56 days and then challenged with C. perfringens three times. Our results indicate that the addition of MS-SB or SB before C. perfringens infection significantly decreased the thymus index (p < 0.05). Serum IgA, IgY, and IgM concentrations were significantly increased (p < 0.05), while pro-inflammatory IL-1β, IL-6, and TNF-α were significantly decreased (p < 0.05) under MS-SB or SB supplementation. Compared with SB, MS-SB presented a stronger performance, with higher IgA content, as well as a lower IL-1β level when normal or C. perfringens-challenged. While C. perfringens challenge significantly decreased the villus height (p < 0.05), MS-SB or SB administration significantly increased the villus height and villus height/crypt depth (V/C ratio) (p < 0.05). Varying degrees of SB or MS-SB increased the concentrations of volatile fatty acids (VFAs) during C. perfringens challenge, where MS-SB presented a stronger performance, as evidenced by the higher content of isovaleric acid and valeric acid. Microbial analysis demonstrated that both SB or MS-SB addition and C. perfringens infection increase variation in the microbiota community. The results also indicate that the proportions of Bacteroides, Faecalibacterium, Clostridia, Ruminococcaceae, Alistipes, and Clostridia were significantly higher in the MS-SB addition group while, at same time, C. perfringens infection increased the abundance of Bacteroides and Alistipes. In summary, dietary supplementation with SB or MS-SB improves the immune status and morphology of intestinal villi, increases the production of VFAs, and modulates cecal microbiota in chickens challenged with C. perfringens. Moreover, MS-SB was more effective than SB with the same supplemental amount.

With 80% of bacterial infections occurring as biofilms, biofilm-related infections have evolved into a critical public health concern. Probiotics such as Bacillus licheniformis have emerged as promising alternatives, offering new avenues for effective treatment. This study aimed to evaluate the activity of licheniformis against the growth, biofilm formation, motility, and quorum sensing (QS) of Salmonella typhimurium. Several experiments were conducted: The minimum inhibitory concentration (MIC) of Bacillus licheniformis against Salmonella typhimurium was determined to be 0.5 mg/mL using the broth microdilution method. The inhibition zone of 100 mg/mL of B. licheniformis against Salmonella typhimurium was 19.98 ± 1.38 mm; the time-growth curve showed that B. licheniformis can effectively inhibit the growth of Salmonella typhimurium. In biofilm experiments, at the MIC of B. licheniformis, the inhibition rate of immature biofilm of Salmonella typhimurium was 86.9%, and it significantly reduced the production of biofilm components (EPS, e-DNA, and extracellular proteases) (p < 0.05). The disruption rate of mature biofilm by B. licheniformis at the MIC was 66.89%, and it significantly decreased the levels of biofilm components (EPS and e-DNA) (p < 0.5). Microscopic observation showed that both the MIC and 1/2 MIC of B. licheniformis could reduce the number of bacteria in the Salmonella typhimurium biofilm, which was not conducive to the formation and maintenance of the biofilm structure. Swimming/Swarming assays and QS experiments confirmed that B. licheniformis inhibits the motility of Salmonella typhimurium and the secretion of AI-1-type quorum sensing molecules and downregulates the AI-2 quorum sensing system by upregulating lsr gene expression. These findings suggest that B. licheniformis could be a potential antimicrobial agent and biofilm inhibitor.

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 (p < 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) (p < 0.05). PQQ modulated gut microbiota, increasing Lactobacillus and Bifidobacterium, and elevated short-chain fatty acid production (p < 0.05). Metabolomic analysis revealed upregulated tricarboxylic acid (TCA) cycle intermediates (citric acid, isocitric acid and malic acid), indicating improved mitochondrial function (p < 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.