Effects of dietary supplementation with Bacillus subtilis LS 1–2 fermentation biomass on growth performance, nutrient digestibility, cecal microbiota and intestinal morphology of weanling pig

The present study investigated the effects of dietary supplementation with Bacillus subtilis LS 1–2 and citrus-juice waste fermentation biomass (BS 1–2 fermentation biomass) on growth performance, coefficient of total tract apparent digestibility (CTTAD) of nutrients, serum immunoglobulins, cecal microbiota and intestinal morphology of weanling pigs. A total of 240 weaned pigs (Landrace×Yorkshire×Duroc, initial body weight (BW): 6.4±0.5kg; 21 days of age) were randomly allotted to 4 treatments on the basis of BW (4 pens per treatment with 15 pigs in each pen). The dietary treatments included a basal diet supplemented with 0 (control), 1.5, 3.0 or 4.5g/kg BS 1–2 fermentation biomass. The experimental diets were fed in a meal form for 2 phases (days 0–14, phase I and days 14–28, phase II). Pigs fed increasing dietary concentrations of BS 1–2 fermentation biomass had linear improvement (P<0.05) in overall average daily gain (ADG), average daily feed intake (ADFI), gain:feed (G:F) and CTTAD of dry matter (DM), gross energy (GE) and crude protein (CP). Also, overall ADG and ADFI of pigs fed 3.0 and 4.5g/kg diets BS 1–2 fermentation biomass were greater (P<0.05) than pigs fed the control diet; whereas, G:F and CTTAD of DM, GE and CP of pigs fed 4.5g/kg diet BS 1–2 fermentation biomass were greater (P<0.05) than pigs fed the control diet. At days 14 and 28, dietary increasing levels of BS 1–2 fermentation biomass linearly increased (P<0.05) serum IgG and IgA concentrations. At days 28, pigs fed increasing dietary concentrations of BS 1–2 fermentation biomass had fewer (linear, P<0.05) cecal Clostridium spp. and coliforms. Moreover, pigs fed the 4.5g/kg diet BS 1–2 fermentation biomass had fewer (P<0.05) cecal Clostridium spp. and coliforms than pigs fed the control diet. On day 28, there was a significant linear effect of treatment on the villus height and villus height:crypt depth (VH:CD) of the duodenum, jejunum and ileum of pigs. Pigs fed the diet supplemented with 4.5g/kg BS 1–2 fermentation biomass had greater (P<0.05) villus height and VH:CD (duodenum, jejunum and ileum) than those fed the control diet. The results suggest that BS 1–2 fermentation biomass had beneficial effects on weanling pigs growth performance, CTTAD of nutrients, cecal microbiota, serum immunoglobulins and intestinal morphology. Additionally, citrus-juice waste can be used as a substrate for growth of probiotic B. subtilis LS 1–2 under solid substrate fermentation.