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

Canola meal (CM) is widely produced in Canada, but its use in swine diets is limited due to the presence of anti-nutritional factors (ANFs). This study investigated whether solid-state fermentation (SSF) with two Bacillus subtilis strains, BS9 and L5, could improve the nutritional quality of CM and its functional effects in nursery pigs. Canola meal was fermented with each strain for 48 hours and then incorporated into a six-week feeding trial consisting of four diets: negative control (NC), 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 the NC phase 2 diet in weeks 5 and 6 to assess any residual effects. Individual body weight and weekly feed intake were recorded throughout the study. Fermentation increased temperature and pH, and significantly reduced phytic acid, NDF, and glucosinolates while improving crude protein, soluble protein, and mineral availability. In the in vivo trial, the average body weight did not differ among treatments. BS9-FCM maintained performance comparable to the PC during the treatment period. Two weeks after the treatment was off by week 6, BS9-FCM showed an improved feed conversion ratio (FCR) compared to the ZnO supplemented control. On the other hand, the average daily gain (ADG) and feed conversion rate in L5-FCM were lower than those in the PC in week 2 and week 4, but no different when compared to the NC group. Fermented CM reduced ileal gene expression of the pro-inflammatory chemokine IL8 in both BS9 and L5 groups, while downregulation of the innate immune receptor TLR4 was observed only in BS9-FCM. Overall, Fermentation of CM decreased ANFs, enhanced nutrient composition, modulated the gut microbiota, supported immune function, and improved feed efficiency in nursery pigs. Fermented CM shows promise as a functional swine feed ingredient.