Due to the lack of corn and soybean meal in animal feeding, rice bran meal (RBM) has been proposed as a beneficial substitute for these feedstocks’ ingredients. Its fermentation by using diverse microbes has been adopted as a beneficial technique. In this study, 18 five-month-old finishing pigs (castrated Duroc × Landrace × Large White) were assigned to three dietary groups with six replicates in each group, designated as the control (CON), unfermented RBM (RBM), and fermented RBM (FRBM) groups. RBM was fermented with a mixture of Lactobacillus johnsonii L63 and hydrolytic enzymes at 37 °C and pH 4.8 for 60 h. The results indicated that incorporating 30% fermented or unfermented rice bran meal into the diets of finishing pigs had no significant effect on growth performance. Regarding serum biochemical parameters, most indicators, including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and triglycerides, showed no significant alterations. However, in both the unfermented and fermented rice bran meal groups, the concentrations of serum total protein, albumin, globulin, cholesterol, and blood urea nitrogen were significantly decreased (p < 0.05), whereas serum nitric oxide levels were significantly increased (p < 0.05). The FRBM group improved intestinal morphology and the digestibility of nutrients (crude protein, ether extract, crude fiber, and gross energy) by altering the mTORC1 pathway and upregulating the relative expression of amino acid and peptide transporter genes in the jejunum. However, the dry matter digestibility decreased compared to the CON group. The RBM group reduced nutrient digestibility, along with alterations in hepatic gene expression related to amino acid metabolism and transport. Therefore, fermented rice bran meal may offer a potential substitute feed ingredient for use in swine diets when conventional ingredients like corn and soybean meal are in short supply.

Co-fermentation with bacteria and enzymes can reduce sugar content in palm kernel cake (PKC); however, the chemical changes and their effects on cell functionality are unclear. This study investigated the active components in pre-treated PKC extracts and their effects on pig small intestine IPEC-J2 cell proliferation and LPS-induced inflammation. The extracts contained 60.75% sugar, 36.80% mannose, 1.75% polyphenols and 0.59% flavone, as determined by chemical analyses, suggesting that the extracts were palm kernel cake oligosaccharides (PKCOS). Then, we found that 1000 µg/mL PKCOS counteracted the decrease in cell viability (CCK8 kit) caused by LPS induction by 5 µg/mL LPS (p < 0.05). Mechanistic studies conducted by RNA-seq and qPCR analyses suggested PKCOS promoted cell proliferation through the upregulation of TNF-α, PI3KAP1, MAP3K5 and Fos in the PI3K/MAPK signalling pathway; alleviated inflammation caused by LPS via the downregulation of the target genes Casp3 and TNF-α in association with apoptosis; and regulated the expression of the antioxidant genes SOD1, SOD2 and GPX4 to exert positive antioxidant effects (p < 0.05). Furthermore, PKCOS upregulated SLC5A1 (encoding SLGT1), HK and MPI in the glycolytic pathway (p < 0.05), suggesting cell survival. In summary, PKCOS has positive effects on promoting swine intestine cell proliferation against inflammation.