This study evaluated the effect of in ovo Bacillus spp. base probiotic (BBP) administration on hatchability, Gram-negative bacteria (GNB) recovery, performance, and microbiota composition in 2 independent trials using a virulent E. coli seeder challenge model. In each trial, one hundred and eighty 18-day-old embryos were allocated into 1 of 2 groups: Control and treated group (inoculated with 107 BBP). On day 19 of embryogenesis, seeder embryos (n = 18) were inoculated with 4.5 × 104E. coli/mL+272 μg/mL tetracycline and segregated into mesh hatching bags. Twelve chicks per group were euthanized at hatch and at day 7 to evaluate the gastrointestinal composition of total GNB or total aerobic pasteurized bacteria. Also, in trial 2, ceca content from five chickens at day 7 were collected to evaluate microbiota composition. Embryos inoculated with BBP showed a significant (P < 0.05) reduction in the total number of GNB at day-of-hatch (DOH) and day 7. Probiotic treatment increased BW at DOH and day 7, and BW gain (days 0 to 7) when compared with Control chickens. Proteobacteria phylum was significantly reduced, while the Firmicutes was significantly increased by the BBP as compared to the Control (P < 0.05). At family level, Enterobacteriaceae was significantly decreased, while the Lachnospiraceae was significantly elevated in the BBP as compared to the Control group (P < 0.05). The genus Oscillospira was significantly enriched in the BBP group, whereas the unidentified genus of family Enterobacteriaceae in the Control group (P < 0.05). The BBP group increased the bacterial species richness, although there was no significant difference between treatments (P > 0.05). Interestingly, beta diversity showed a significant difference in bacterial community structure between Control and BBP groups (P < 0.05). The results of the present study suggest that in ovo administration of a BBP can reduce the severity of virulent E. coli horizontal transmission and infection of broiler chickens during hatch. The reduction in the severity of the transmission and infection by the BPP might be achieved through alterations of microbiota composition and its community structure.

中文翻译：

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卵内芽孢杆菌属的评估。基于益生菌给药对新生肉鸡中毒性大肠杆菌水平传播的影响。

本研究评估了卵内芽孢杆菌属的效果。在使用毒性大肠杆菌播种机挑战模型的 2 项独立试验中，基于孵化率、革兰氏阴性菌 (GNB) 恢复、性能和微生物群组成的益生菌 (BBP) 施用。在每个试验中，180 个 18 天大的胚胎被分配到 2 组中的 1 组：对照组和治疗组（接种 107 BBP）。在胚胎发生的第 19 天，播种机胚胎 (n = 18) 接种了 4.5 × 104E。大肠杆菌/mL+272 μg/mL 四环素并分离到网状孵化袋中。每组 12 只小鸡在孵化时和第 7 天处以安乐死，以评估总 GNB 或总需氧巴氏杀菌细菌的胃肠道组成。此外，在试验 2 中，收集了第 7 天五只鸡的盲肠含量以评估微生物群组成。接种 BBP 的胚胎在孵化日 (DOH) 和第 7 天显示 GNB 总数显着减少 (P < 0.05)。益生菌处理在 DOH 和第 7 天增加了体重，并增加了体重 (第 0 至 7 天) 与对照鸡相比。与对照相比，BBP 显着减少了变形菌门，而厚壁菌门则显着增加（P < 0.05）。在家族水平上，与对照组相比，BBP 中肠杆菌科显着减少，而毛螺菌科显着升高（P < 0.05）。BBP组中震旋螺旋体属显着富集，而对照组中未鉴定的肠杆菌科属(P < 0.05)。BBP组增加了细菌种类丰富度，处理间差异不显着（P > 0.05）。有趣的是，β 多样性显示对照组和 BBP 组之间细菌群落结构存在显着差异（P < 0.05）。本研究的结果表明，卵内施用 BBP 可以降低肉鸡在孵化期间的毒性大肠杆菌水平传播和感染的严重程度。可以通过改变微生物群组成及其群落结构来降低 BPP 传播和感染的严重程度。肉鸡孵化过程中大肠杆菌的水平传播和感染。可以通过改变微生物群组成及其群落结构来降低 BPP 传播和感染的严重程度。肉鸡孵化过程中大肠杆菌的水平传播和感染。可以通过改变微生物群组成及其群落结构来降低 BPP 传播和感染的严重程度。