Effects of Replacing Soybean Meal with Fermented Rapeseed Meal on Growth Performance, Meat Quality, Intestinal Morphology and Short-Chain Fatty Acid Production in Finishing Pigs

The objective of this study was to evaluate the effects of fermented rapeseed meal (FRSM) replacing soybean meal (SBM) on growth performance, carcass traits, meat quality, serum biochemical parameters, and intestinal morphology in finishing pigs. Fifty healthy barrows (Duroc × Landrace × Yorkshire, DLY) were randomly assigned to five groups (n = 10): group A (control, soybean meal-based diet with 0% FRSM) and groups B, C, D, and E with 2.8%, 5.6%, 8.4%, and 11.2% FRSM inclusion, respectively. FRSM inclusion had no significant effect on growth performance. Compared with group A, group C showed greater bone weight and backfat thickness (p < 0.05), whereas group D had a lower dressing percentage (p < 0.05). Meanwhile, group D showed improved pressing loss and increased levels of arachidonic acid and α-linolenic acid (p < 0.05). Serum analysis revealed reduced malondialdehyde and elevated alanine, methionine, lysine, and cysteine concentrations in group D (p < 0.05). Jejunal villus height and villus height-to-crypt depth ratio were significantly increased in groups D and E, indicating improved intestinal morphology. However, group E reduced colonic acetic acid concentration. Adding 8.4% FRSM improved fatty acid composition, meat quality, and intestinal structure without compromising growth performance, suggesting that FRSM is a viable and sustainable alternative protein source in finishing pig diets.