Department of Animal Science, Iowa State University, Ames, IA.
J Anim Sci. 2020 Jan 1;98(1). doi: 10.1093/jas/skz383.
Probiotic feed additives with potential to enhance performance, health, and immunity have gained considerable popularity in commercial broiler production. The study objectives were to measure broiler performance, gut integrity, and splenic immune cell profiles in birds fed one of two probiotics at two inclusion levels. Nine hundred sixty Ross 708 broilers (12 per pen) were randomly assigned to no additive control, 0.05% or 0.10% LactoCare (Lactobacillus reuteri), or 0.05% or 0.10% LactoPlan (Lactobacillus plantarum) dietary treatments for 6 wk. On day 27, a 20-pen subset was utilized for a fluorescein isothiocyanate dextran (FITC-d) assay, where half of the pens were subject to a 12-h feed restriction (FR) pregavage. Serum collected from blood drawn 1-h postgavage was analyzed for relative fluorescence of FITC-d absorbed across the intestinal barrier as a gut leakiness indicator. On day 42, spleens from eight birds per treatment were collected for immune cell profile analysis by multicolor flow cytometry. Although performance outcomes were not affected by dietary treatment, FITC-d absorption post-FR was increased 57% in the 0.05% LactoPlan treatment, and was decreased by 12.6% in the 0.05% LactoCare diet, 12% in the 0.10% LactoCare diet, and 22% in the 0.10% LactoPlan diet compared with the control. This indicates a positive impact in barrier integrity maintenance due to 0.05% and 0.10% LactoCare and 0.10% LactoPlan diet following a challenge. Immune cell profiles varied between the two probiotic compositions, with an approximately 50% reduction in splenic innate immune cells (monocyte/macrophage+) in birds fed LactoPlan (P < 0.0001) and greater overall percentages of CD45+ leukocytes and CD3+ T cells in birds fed 0.10% LactoCare (P < 0.0001). LactoPlan diets shifted splenic T-cell populations in favor of CD8α + cytotoxic T cells (TC; P = 0.007), while higher inclusions (0.10%) of either probiotic increased the percentage of activated CD4+ helper T cells (TH; P < 0.0001). These results indicate that compositionally different probiotics had varying effects on the gut permeability and splenic immune cell profiles in broiler chickens, particularly at higher inclusion rates, but observed changes to underlying physiology did not negatively impact performance outcomes. The ability of a probiotic to alter gut permeability and immune cell profile, therefore, may depend on the compositional complexity of the product as well as inclusion rate.
益生菌饲料添加剂具有提高生产性能、健康和免疫力的潜力，在商业肉鸡生产中得到了广泛的关注。本研究的目的是测量在两种益生菌的两种添加水平下，肉鸡的生产性能、肠道完整性和脾脏免疫细胞特征。将 960 只 Ross 708 肉鸡（每笼 12 只）随机分配到无添加剂对照组、0.05%或 0.10% LactoCare（鼠李糖乳杆菌）或 0.05%或 0.10% LactoPlan（植物乳杆菌）日粮处理组，进行 6 周。在第 27 天，利用 20 个鸡笼的子集进行荧光素异硫氰酸酯葡聚糖（FITC-d）测定，其中一半鸡笼进行 12 小时的饲料限制（FR）预灌胃。在 FR 预灌胃后 1 小时采血，分析血清中 FITC-d 的相对荧光强度，作为肠道通透性的指示。在第 42 天，从每个处理组的 8 只鸡中收集脾脏，通过多色流式细胞术分析免疫细胞特征。尽管日粮处理对生产性能没有影响，但 0.05% LactoPlan 处理的 FR 后 FITC-d 吸收增加了 57%，而 0.05% LactoCare 日粮降低了 12.6%，0.10% LactoCare 日粮降低了 12%，0.10% LactoPlan 日粮降低了 22%，与对照组相比。这表明，由于在挑战后添加 0.05%和 0.10% LactoCare 和 0.10% LactoPlan 日粮，维持了屏障完整性，因此具有积极的影响。两种益生菌制剂之间的免疫细胞特征不同，饲喂 LactoPlan 的鸡脾脏固有免疫细胞（单核细胞/巨噬细胞+）减少了约 50%（P<0.0001），饲喂 0.10% LactoCare 的鸡的 CD45+白细胞和 CD3+T 细胞的总百分比更高（P<0.0001）。LactoPlan 日粮使脾脏 T 细胞群向 CD8α+细胞毒性 T 细胞（TC）倾斜（P=0.007），而较高的益生菌含量（0.10%）增加了活化的 CD4+辅助 T 细胞（TH）的百分比（P<0.0001）。这些结果表明，组成不同的益生菌对肉鸡的肠道通透性和脾脏免疫细胞特征有不同的影响，特别是在较高的添加率下，但观察到的生理变化并没有对生产性能产生负面影响。益生菌改变肠道通透性和免疫细胞特征的能力，因此可能取决于产品的组成复杂性以及添加率。
