Bile acids play a dual role by aiding lipid absorption and acting as signaling molecules by interacting with various receptors. Bile acids are perpetually recycled via enterohepatic circulation and are biotransformation by gut microbiota, making bile acid metabolism a critical regulator of intestinal homeostasis. The intestinal epithelium prominently expresses two key bile acid receptors - the farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (TGR5) - which play indispensable roles in maintaining bile acid homeostasis and intestinal barrier function. Due to the abundant expression of bile acid receptors and the importance of the intestine in preventing pathogen invasion, researchers are increasingly focused on the function of bile acids in this system. This article focuses on the effect of bile acids and their receptors, FXR and the TGR5, in modulating intestinal barrier function.

The intestinal immune barrier is a developed and complex immune system, and there is a fine synergy between it and the induced immune response. Short-chain fatty acids (SCFAs) are the main metabolites of intestinal microbial fermentation. In the cecum of pigs, SCFAs not only provide energy for the host but also participate in regulating the function of the intestinal immune system. The purpose of this study was to explore the mechanism of SCFAs in the regulation of immune gene expression in porcine cecum. SCFAs content and mRNA expression levels of immune genes in cecum were detected, and Gene Ontology (GO) function annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, Protein-Protein Interaction Networks (PPI) network construction, key gene identification, and correlation analysis were performed. The results showed that the content of SCFAs in the cecum of Dahe black pigs (DHB) was lower than that of Dahe pigs (DH). There were significant differences in mRNA expression of some immune genes between the two groups. GO functional annotation found terms related to cytokine activity and protein heterodimerization activity; the KEGG pathway was enriched in several pathways related to intestinal immunity. The PPI network identified Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Interleukin-17A (IL-17A), and Interleukin-18 (IL-18) as key proteins. The correlation analysis showed that acetic acid and valerate were closely related to the immune response. In this study, the differences in cecal short-chain fatty acids and the immune barrier between Dahe pigs and Dahe black pigs were compared, which provided a theoretical basis for improving the intestinal immunity of pigs.

Yucca schidigera extract (YSE) is a plant-derived feed additive rich in steroidal saponins, polyphenols, and polysaccharides, with demonstrated anti-inflammatory, antioxidant, antibacterial, and ammonia-binding properties. This review systematically synthesizes the major bioactive components, core mechanisms of action, including modulation of the Nrf2/ARE and NF-κB pathways, regulation of ruminal fermentation and ammonia-nitrogen metabolism, and maintenance of intestinal barrier integrity, and the species-specific application effects of YSE in pigs, poultry, ruminants, and aquatic animals. Most studies have shown that YSE can improve growth performance, reproductive efficiency, and product quality while concurrently reducing ammonia and methane emissions. However, the magnitude and consistency of these benefits vary considerably across species, dosage, and experimental conditions, with most evidence derived from controlled trials rather than commercial-scale validation. By integrating cross-species dose–response data and identifying critical knowledge gaps, including product standardization, long-term safety, and economic feasibility under commercial conditions, this review provides a theoretical and practical foundation for the evidence-based application of YSE as a sustainable feed additive. In the context of global efforts to reduce antibiotic use and mitigate environmental pollution from livestock production, YSE represents a promising, multifunctional tool for advancing ecological and low-carbon animal husbandry.

Oxidative stress constitutes a key restrictive factor that undermines growth performance, reproductive efficiency and meat quality throughout the entire production cycle of commercial pig herds. Vitamin A (VA), an essential fat-soluble nutrient for pigs, fulfills dual antioxidant regulatory functions: it directly scavenges free radicals, and indirectly mediates transcriptional regulation of antioxidant processes via retinoic acid receptor-associated signaling pathways. By integrating recent in vivo feeding trial data and in vitro molecular experimental evidence, this review demonstrates that the antioxidant effect of VA in pigs is characterized by significant stress dependence, dose responsiveness and physiological stage specificity. Under stress challenge conditions, VA can significantly upregulate the body’s antioxidant response, while its regulatory effect is relatively weak under non-stress basal physiological conditions. From the mechanistic perspective, all-trans retinoic acid (ATRA) bound to RAR/RXR receptors can exert synergistic effects with the Nrf2 antioxidant pathway when VA is supplied at physiological nutritional doses, whereas high pharmacological doses of ATRA may induce competitive inhibitory crosstalk. It should be noted that most existing direct promoter-binding evidence is derived from cell line models rather than in vivo porcine tissue samples. For weaned piglets, an optimal dietary VA level can alleviate oxidative damage and intestinal barrier impairment induced by weaning stress, but excessive VA supplementation will trigger lipotoxic oxidative disturbance. In growing-finishing pigs, appropriate VA supplementation can increase glutathione (GSH) content in skeletal muscle and improve the lipid oxidation stability and color stability of pork during post-mortem storage; however, supra-nutritional VA will compete with vitamin E for tissue deposition, which may in turn impair the storage quality of pork. For sows, most existing studies on the reproductive antioxidant effect of VA are derived from intramuscular injection trials, and data from practical dietary VA intervention studies are still insufficient. Existing evidence indicates that maternal VA can regulate the transfer of retinol to offspring via the placenta and colostrum-milk, but no consistent dose-response relationship has been confirmed to date. Meanwhile, relevant research in breeding boars remains extremely insufficient. In terms of nutrient interaction, VA shows antioxidant synergistic effects with vitamin E, vitamin C and selenium, while excessive intake of dietary vitamin D, copper or zinc will reduce the bioavailability of VA and weaken its antioxidant protective effect. Current research in this field is constrained by prominent inter-study heterogeneity, insufficient verification of in vivo molecular mechanisms in pigs, and the absence of antioxidant-targeted VA feeding standards adapted to diverse stress scenarios. The systematic summary of the above findings provides an important reference for the formulation of precision antioxidant nutritional strategies for commercial pig herds. To address the current knowledge gaps, future research should focus on constructing standardized porcine experimental stress models, applying multi-omics technical means to dissect tissue-specific VA antioxidant regulatory networks, clarifying the mechanism of maternal-offspring VA transfer under graded dietary VA intake, and optimizing compatible dosage forms and nutrient combinations adapted to on-farm application scenarios. The advancement of related research will help alleviate production losses caused by oxidative stress and promote the construction of healthy pig production systems.

Background/Objectives: Panax notoginseng stems and leaves (PNSLs) have shown limited adoption as a forage component in commercial livestock operations due to low utilization rates. Methods: This study was designed to add 10% and 20% PNSLs in the diet of Duzang pigs. Hepatic tissues were collected to investigate the expression levels of Toll-like receptor (TLR), MyD88, TRIF genes, and downstream cytokines within the TLR signaling pathway. Results: 10% and 20% PNSLs in the diet significantly up-regulated mRNA expression levels of TLR3, TLR6, TLR7, TLR8, TRIF, IL-10, IFN-α and IFN-β, while they down-regulated TLR5, TLR9, TNF-α and IL-1β in Duzang pigs. No significant effects were observed on the expression of TLR2 and IL-6. Conclusions: Different amounts of PNSLs modulated the TLR signaling pathway mRNA expression levels in the hepatic tissues of Duzang pigs.

This research systematically compared the jejunum morphology, antioxidant capacity, barrier-related gene expression, and mucosal immune status between two Yunnan local pig breeds, namely Dahe pigs (DH) and Dahe black pigs (DHB), using histopathological staining, antioxidant assays, quantitative polymerase chain reaction (qPCR), immunofluorescence, and enzyme—linked immunosorbent assay (ELISA). The outcomes indicated that DHB presented a shallower crypt depth and a higher ratio of villus height to crypt depth, suggesting an enhanced capacity for nutrient absorption. In their jejunum, the activities of glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) were significantly elevated, whereas the levels of malondialdehyde (MDA) were notably reduced. Conversely, DH displayed superior barrier function, with significantly higher expression levels of tight-junction proteins (Occludin, OCLN; Claudin-1, CLDN1 and Claudin-2, CLDN2) , mucin genes ( MUC1 ), defense-related proteins ( DEFB1, DEFB2 ), and immune-related genes (Interleukin-10, IL-10; Toll-like receptor 4, TLR4; Myeloid differentiation factor 88, MyD88; Immunoglobulin heavy chain A, IGHA; Joining chain, JCHAIN and Polymeric immunoglobulin receptor, PIGR ), along with a significant increase in IgG levels ( p < 0.05). These findings uncover the distinct physiological and immunological characteristics between the two breeds, offering theoretical underpinnings for precision nutrition and healthy breeding strategies in local pig populations.