Early weaning can disrupt the intestinal function and microbial community balance of piglets, and trigger inflammation and oxidative stress, thereby affecting their production performance. In recent years, butyric acid has gained considerable interest as a functional feed additive. However, practical limitations such as its pungent odor and low absorption efficiency in the digestive tract have led to the development of more stable forms, including sodium butyrate, coated butyrate, and butyrate glycerides, etc. Research has shown that butyric acid and its derivatives can serve as effective feed additives by enhancing pigs’ resistance to pathogenic colonization, stabilizing the intestinal microbiota, and alleviating oxidative stress to mitigate challenges such as weaning stress and pathogenic infections. This review systematically highlights the role of butyric acid and its derivatives as dietary supplements for weaned piglets. Importantly, it underscores the potential of butyric acid and its derivatives may contribute to antibiotic-reduction strategies in weaned piglet nutrition, while also highlighting the need for optimized supplementation strategies and further investigation into synergistic effects with other feed additives. This review aims to offer both theoretical and practical insights for the application of butyric acid in weaned piglet nutrition.

Staphylococcus aureus (S. aureus)-induced mastitis poses a severe threat to the global dairy industry and raw milk safety. This study aimed to evaluate the protective effects of lytic phage JXAU-SA-P1, recently isolated in our laboratory, against S. aureus-induced mastitis in mice and to elucidate its underlying mechanisms. A total of 42 lactating BALB/c mice (7–10 days postpartum) were allocated into seven groups (n = 6) to assess bacterial reduction, tissue pathology, and host immune responses following intramammary S. aureus challenge. The results showed that JXAU-SA-P1 significantly reduced S. aureus burdens and alleviated mammary histopathological damage, with better efficacy than antibiotic therapy. Safety assessments showed that JXAU-SA-P1 was steadily cleared in the absence of host bacteria without triggering inflammation response. Transcriptomic profiling identified 448 overlapping differentially expressed genes (DEGs) modulated by high-dose phage administration. Gene set enrichment analysis (GSEA) revealed that phage administration suppressed major pro-inflammatory pathways, including the TNF, NF-kappa B, and IL-17 signaling pathways. Core regulatory hub genes, including IL-1β, Ptprc, Itgam, Fcgr3, and Itgb2, were identified through protein–protein interaction network analysis. Subsequent ELISA confirmed significant reductions in pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β), the neutrophil infiltration marker myeloperoxidase (MPO), and serum immunoglobulins (IgA, IgM, and IgG). In conclusion, phage JXAU-SA-P1 effectively alleviated mastitis through direct pathogen lysis and subsequent alleviation of the host inflammatory response, providing a strong experimental foundation for the development of phage-based products as safe, antibiotic-free biocontrol agents for dairy production.

The present study evaluated the effects of dietary selenium sources on growth performance, slaughter traits, meat quality, tissue selenium deposition, and transcriptomic profiles in the longissimus dorsi muscle of Tibetan pigs. Seventy-two Tibetan pigs (initial body weight: 41.96 ± 6.91 kg) were randomly allocated to four treatment groups receiving 0.5 mg/kg selenium as either sodium selenite (SeS), selenium-enriched yeast (SeY), selenium-enriched seaweed polysaccharide (SeSP), or nano-selenium (SeN) for 60 days. Results showed that neither growth performance nor slaughter traits differed significantly among the four treatments (p > 0.05). Likewise, meat quality parameters of the longissimus dorsi remained comparable across groups, with the exception of drip loss, which was significantly increased in the SeN group compared with the SeS, SeY, and SeSP groups (p < 0.05), among which no differences were observed (p > 0.05). Importantly, selenium contents in the kidney, liver, heart, and longissimus dorsi were markedly elevated in the SeY group relative to the other three groups (p < 0.05). Longissimus dorsi transcriptome analysis identified 34 overlapping differentially expressed genes (DEGs) among the three pairwise comparisons (SeS vs. SeY, SeSP vs. SeY, and SeN vs. SeY), such as S100A1, S100A6, and COL22A1 (p < 0.05). Functional enrichment analysis revealed that response to external stimulus and extracellular region (GO terms), as well as viral protein interaction with cytokine and cytokine receptor (KEGG pathway), represented shared enriched annotations across all comparisons. In conclusion, selenium-enriched yeast at 0.5 mg/kg proved superior to the alternative selenium sources in promoting selenium bioaccumulation in longissimus dorsi of Tibetan pigs. The resultant selenium-enriched muscle tissue exhibited potential beneficial functions including external stimulus response, extracellular region homeostasis, and cytokine–cytokine receptor crosstalk.