Transcriptomic analysis reveals jejunal mechanisms underlying postbiotic mediated immune systems in calves

This study aimed to investigate the effect of dietary supplementation with postbiotic from dead cell Lactobacillus ingluviei CR37 (DCLI) on blood biochemical parameters, and jejunal epithelium transcriptomic profiles in calves. Transcriptomic analysis identified 76 DEGs, with significant upregulation of genes involved in fatty acid metabolism (FABP1), intestinal barrier function (B4GALNT2), and detoxification (GSTA1), alongside downregulation of immune response regulation (FCRLA, FCRL4). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses highlighted enrichment in pathways related to Glutathione metabolism, Drug metabolism, and Vitamin digestion, indicating postbiotic supplementation improved detoxification, oxidative stress defense, and nutrient absorption in calves. This study provides novel insights into the molecular mechanisms underlying the benefits of postbiotics and supports their potential as a sustainable alternative to probiotics in calf nutrition Fourteen Holstein bull calves were assigned to 2 treatment groups: CON (n = 7) or DCLI (n = 7, fed 1 g/d of dead cell Lactobacillus ingluviei CR37 strain, containing 108 CFU/g). Calves received milk replacer (MR) at 1.75% of BW (based on air-dry weight) and the amount was adjusted weekly according to body weight, while fresh and clean water was provided ad libitum. All calves had free access to starter starting on day 33. On day 82, the MR solution was reduced to 50% of the previous week's allocation, and calves were completely weaned by day 89. On the last day of the experimental period (d 90), prior to morning feeding. Four calves were randomly selected from each group and euthanized using captive bolt stunning and exsanguinated. The abdominal cavity was quickly opened. The jejunum was defined as starting at 100 cm caudal to the pylorus. Jejunal samples were collected approximately 30 cm proximal to the collateral branch of the cranial mesenteric artery, rinsed three times with sterile phosphate-buffered saline (PBS, pH = 7.0), and immediately placed into sterile RNase-free tubes. The samples were then flash-frozen in liquid nitrogen and stored at -80°C until RNA extraction.