Isomaltooligosaccharide (IMO) and Bacillus regulate serum reproductive hormone concentration in sows at farrowing. (A) Estradiol, (B) progesterone, (C) oxytocin, (D)prolactin, and (E) prostaglandin. Data are presented as means ± SD (n = 7). Values with different lowercase letters (a, b, c) indicate a significant effect of treatment (P < 0.05). CON group, sows fed diets without IMO; IMO group, sows fed diets containing 5.0 g/kg IMO; IMOS group, sows fed diets containing 5.0 g/kg IMO plus 0.2 g/kg Bacillus subtilis; IMOL group, sows fed diets containing 5.0 g/kg IMO plus 0.2 g/kg Bacillus licheniformis; IMOSL group, sows fed diets containing 5.0 g/kg IMO plus 0.2 g/kg B. subtilis and 0.2 g/kg B. licheniformis.