Effects of medium chain fatty acid and yeast extract supplements in pre- and post-weaning in piglets fed diets containing naked oat

• Pre-weaning supplementation with medium-chain fatty acids increased intestinal epithelial proliferation and apoptosis, indicating an overall acceleration of mucosal turnover. • Yeast extract supplementation administered before and after weaning induced mild pro-inflammatory responses and impaired intestinal barrier integrity. • Post-weaning inclusion of naked oat (35% of the diet) significantly enhanced growth performance and feed efficiency, while concurrently reducing inflammatory markers. • Diets containing naked oat shifted the gut microbiota toward beneficial bacterial families (Rikenellaceae and Spirochaetaceae) and improved microbial evenness, whereas medium-chain fatty acid supplementation decreased the abundance of potentially pathogenic Enterobacteriaceae. This study investigated the effects of medium chain fatty acids (MCFA), yeast extract (YE), and naked oats (NO) on growth performance, intestinal health, and gut microbiota of piglets before and after weaning. The experiment consisted of two phases. During lactation, piglets received daily supplements of MCFA (500 mg/d), YE (500 mg/d), a combination of both from d 14 to 19 of lactation, or no supplement. After weaning at 20 d, piglets were assigned to post-weaning diets either containing NO (350 g/kg of diet) or not, and supplemented or not with MCFA (0.1%) and YE (0.1%), creating eight post weaning treatments. Growth performance was monitored, and intestinal mucosa and microbiota samples were analyzed at weaning and 7 d post weaning. Pre-weaning supplementation with MCFA and YE did not improve piglet growth. However, MCFA increased markers of intestinal cell proliferation (proliferating cell nuclear antigen, PCNA; P = 0.008) and apoptosis (caspase-3; P = 0.063), suggesting enhanced mucosal turnover. Yeast extract supplementation increased the inflammatory chemokine C-X-C motif chemokine ligand 10 (CXCL-10; P = 0.003) and decreased occludin ( P = 0.050), a tight junction protein, indicating a mild pro inflammatory response and reduced barrier integrity. Neither MCFA nor YE altered microbiota composition in suckling piglets. After weaning, NO significantly improved average daily gain, ( P = 0.032), feed efficiency ( P = 0.020), and intestinal PCNA concentration ( P =0.019), while reducing CXCL-10 ( P = 0.031), suggesting lower intestinal inflammation. Naked oat also increased microbial evenness (Shannon index; P = 0.020) and shifted bacterial communities (beta diversity, P = 0.064) toward families previously associated with better growth performance ( Rikenellaceae and Spirochaetaceae; P < 0.05). In contrast, MCFA and YE supplements did not enhance growth. Yeast extract decreased villus height and occludin concentrations, especially in absence of MCFA supplement (MCFA × YE, P = 0.037; P = 0.050) but increased caspase 3 ( P = 0.019). Combination of MCFA and YE increased oxidative stress marker malondialdehyde (MDA; MCFA × YE, P = 0.018), while MCFA also lowered the abundance of potentially harmful bacterial families ( Enterobacteriaceae, P < 0.05). Overall, the study concludes that pre weaning supplementation with MCFA or YE does not improve growth and may induce mixed intestinal responses. Post weaning, however, incorporating NO at 35% of the diet is beneficial for performance, mucosal health, and microbiota structure. While MCFA and YE affected specific biological pathways, their inclusion at tested levels did not enhance growth and requires further evaluation.