Effects of Bacillus subtilis fermented canola meal on nutritional characteristics and growth performance of nursery pigs

Canola meal (CM) is a valuable protein source with strong potential to partially replace conventional protein ingredients in swine diets. However, its application is limited by the presence of anti-nutritional factors (ANFs). This study investigated whether fermentation with two probiotic Bacillus subtilis strains, BS9 and L5, which our team recently isolated, could improve the nutritional quality of CM and confer functional benefits in nursery pigs. The CM was first fermented with each strain for 48 h and subsequently incorporated into a six-week feeding trial in weaning pigs. The trial has four groups: negative control, positive control with 0.03% ZnO (PC), 15% BS9-fermented CM (BS9-FCM), and L5-fermented CM (L5-FCM). Pigs were fed treatment diets for four weeks, followed by an additional two-week (weeks 5 and 6) trial in which all the pigs were fed the same diet without fermentation treatment to assess any residual effects. Individual BW and weekly feed intake were recorded throughout the study. CM fermentation increased temperature and pH and improved CM nutritional characteristics. Fermentation significantly reduced the ANFs such as phytic acid, NDF, and glucosinolates while improving CP, soluble protein, and mineral availability. In the in vivo trial, BS9-FCM maintained performance similar to the ZnO supplement positive control (PC) group during the treatment period. In week 6, BS9-FCM showed an enhanced feed conversion ratio compared to PC. In week 6, L5-FCM significantly reduced the E. coli counts in faecal samples. Fermented CM also reduced ileal gene expression of the pro-inflammatory chemokine IL8 in both BS9 and L5 groups, and downregulation of the innate immune receptor TLR4 was observed in BS9-FCM, indicating immunomodulatory effects. Overall, fermentation of CM effectively reduced ANFs and improved nutrient composition, with a later feed efficiency benefit for BS9 and changes in intestinal inflammatory gene expression. Our findings suggest that fermentation with selected probiotics can be an efficient approach to improve CM nutritional value.