Two consecutive feeding trials were conducted to evaluate the effects of Bacillus subtilis LCBS1 supplementation and substituting fish meal (FM) with fermented soybean meal (FSM) in terms of growth performance, feed digestibility, intestinal morphology, and microbial composition of bullfrogs. In trial 1, bullfrogs received either a soybean meal (SM)-based basal diet (control check, CK group) or probiotic diet (basal diet was supplemented with 1 × 10⁷ CFU/g of B. subtilis LCBS1, BS group). Each diet was fed to three replicates of bullfrogs (29.61 ± 0.07 g) for 58 days. Evaluation of B. subtilis LCBS1 FSM as a FM replacer in bullfrog diet was conducted in trial 2. A diet containing 20% FM formed the basal diet, and 60% and 100% of the FM was replaced with SM or FSM (FM, SM60, FSM60, SM100, and FSM100 diets). Each diet was fed to three replicates of bullfrogs (23.3 ± 0.3 g) for 63 days. As a result, in trial 1, BS treatments significantly increased weight gain (WG) and whole-body protein deposition. Significant improvements in villus height (VH), muscularis thickness (MT), and digestibilities of dry matter (DM), crude protein (CP) and phosphorus (P) were observed in the BS group compared with the control group. Probiotic supplementation resulted in elevated IL-4 and IL-10 expression and decreased TNF-α and IL-17 expression. A remarkable decrease in serum D-lactate concentration and diamine oxidase activity was detected in the BS group. Proteobacteria, Fusobacteria, and Firmicutes were the three most abundant bacterial phyla in each group, while Enterobacter and Bacillus were the most abundant genera in the CK and BS groups, respectively. In trial 2, compared with bullfrogs that received the SM diets, bullfrogs fed either the FM or FSM diets showed greater WG, feed efficiency, hind leg index, whole-body CP content, and digestibilities of DM, CP, calcium, P, and phytate P, and increased VH, villus thickness, and MT. Serum urea nitrogen and ammonia concentrations were significantly higher in the SM group than the FM or FSM group. Overall, dietary B. subtilis LCBS1 supplementation improved growth and digestion in bullfrogs and attenuated the intestinal structural damage and microflora dysbacteriosis caused by SM-based diets. Substituting 60–100% of FM with SM impaired the growth performance, digestion ability, and jejunal morphology of bullfrogs, while replacing equivalent FM with FSM effectively ameliorated these traits.

进行了两次连续的饲养试验，以评估补充枯草芽孢杆菌LCBS1 和用发酵豆粕 (FSM) 替代鱼粉 (FM) 在牛蛙的生长性能、饲料消化率、肠道形态和微生物组成方面的影响。在试验 1 中，牛蛙接受基于豆粕 (SM) 的基础饮食（对照检查，CK 组）或益生菌饮食（基础饮食中添加 1 × 10 ⁷  CFU/g枯草芽孢杆菌LCBS1，BS 组）。将每种饮食喂给三份重复的牛蛙（29.61 ± 0.07 克），持续 58 天。枯草芽孢杆菌的评价 LCBS1 FSM 作为牛蛙日粮中的 FM 替代品在试验 2 中进行。 含有 20% FM 的日粮形成基础日粮，60% 和 100% 的 FM 被 SM 或 FSM（FM、SM60、FSM60、SM100、和 FSM100 饮食）。将每种饮食喂给三份重复的牛蛙（23.3 ± 0.3 克），持续 63 天。因此，在试验 1 中，BS 治疗显着增加了体重增加 (WG) 和全身蛋白质沉积。与对照组相比，BS组的绒毛高度（VH）、肌层厚度（MT）和干物质（DM）、粗蛋白（CP）和磷（P）的消化率有显着改善。益生菌补充剂导致IL-4和IL-10表达升高并降低TNF-α和IL-17表达。在 BS 组中检测到血清 D-乳酸浓度和二胺氧化酶活性显着降低。Proteobacteria、Fusobacteria 和 Firmicutes 是每组中最丰富的三个细菌门，而Enterobacter和Bacillus分别是 CK 和 BS 组中最丰富的属。在试验 2 中，与接受 SM 日粮的牛蛙相比，饲喂 FM 或 FSM 日粮的牛蛙表现出更高的体重、饲料效率、后腿指数、全身 CP 含量以及 DM、CP、钙、P 和植酸 P，并增加 VH、绒毛厚度和 MT。SM 组的血清尿素氮和氨浓度显着高于 FM 或 FSM 组。总体而言，膳食枯草芽孢杆菌补充 LCBS1 改善了牛蛙的生长和消化，并减轻了由基于 SM 的饮食引起的肠道结构损伤和微生物群落菌群失调。用 SM 代替 60-100% FM 会损害牛蛙的生长性能、消化能力和空肠形态，而用 FSM 代替等效 FM 可有效改善这些性状。