Effect of Creep Feed Supplemented with Bacillus Subtilis on Growth Performance, Blood Inflammatory Cytokines, Gut Permeability, and Fecal Microbiome in Piglets

This study was conducted to evaluate the effects of creep feed supplemented with B. subtilis on growth performance, gut permeability, inflammation response, fecal score, and microbiome of pigs during pre- and post-weaning periods. A total of 12 litters were randomly allotted to 3 treatments based on breed, parity, and litter size at d 2-5 of age. Treatments were: 1) Control (CON): no creep feed, 2) CF: creep feed (24% crude protein) without B. subtilis supplementation, and 3) CFB: creep feed with B. subtilis supplementation at 1.88 × 108 CFU/kg diet. At weaning (22-25 d of age), pigs were moved to the nursery facility within original treatments and fed a common diet in 5 pens per treatment with 5 pigs per pen for 35 d. There were no significant differences in the number of pigs weaned, pig and litter weaning weight, weight gain, and creep feed intake in the suckling period. Throughout the nursery period, the CF group had lower body weight (P = 0.05; 18.17, 17.55, and 17.67 kg for CON, CF, and CFB treatments, respectively) and average daily gain (P < 0.05; 0.475, 0.443, and 0.449, kg/d respectively) in d 0-21 postweaning compared to the CON group, with the CFB group showing no difference from either CON or CF group, and no difference was observed in the overall nursery period. No significant differences were observed in average daily feed intake, gain-to-feed ratio, and fecal score among dietary treatments in the entire nursery period. There were no differences in fecal E. coli count, serum TNF-α, and diamine oxidase levels. Serum levels of IL-1β at weaning (P < 0.05; 57.18, 50.40, and 48.85 pg/mL, respectively) and d-lactate at d 21 postweaning (P = 0.08; 1.341, 0.892, and 0.869 mM, respectively) were lower in the CFB group than the CON group, with the CF group showing no difference from either CON or CFB group. Serum urea nitrogen concentrations at weaning were greater in the CON group than the CF group (P < 0.05; 8.67, 6.00, and 7.00 mg/dL, respectively). The CFB group had greater fecal microbial richness than the CON group at d 21 postweaning (P < 0.05). In conclusion, creep feed with high protein content did not improve postweaning growth, while B. subtilis supplementation had the potential to reduce gut permeability and inflammation and influence fecal microbiome.