The objective of this study was to evaluate the immune effects and the dynamics of intestinal integrity in broilers challenged with Salmonella Enteritidis (SE) and treated continuously with yeast cell wall (YCW). At 4 D posthatch (2 D postinfection [dpi] and poststart of treatment), challenged animals presented the highest intestinal permeability (P < 0.05). The number of circulating leukocytes was highest in the non–SE-challenged groups (P < 0.005). Despite this, challenged broilers consistently presented higher numbers of various cell subtypes, especially at 14 D (Kul01⁻MHC class II⁺, Kul01⁺MHC class II⁺, Kul01⁺MHC class II⁻ cells, and the series of CD4⁺ and CD8⁺ cells). Treatment was effective in evading the reduction of total leukocytes and in preventing some of the immune subset fluctuations provoked by the challenge, such as for Kul01⁻MHC II⁺ and CD8⁺ cells. The number of phagocytic cells was increased by challenge at 6 dpi, while the YCW decreased this effect (P < 0.05). The test group presented the highest number of anti–salmonella IgA–reactive animals, as well as the highest level of IgA (P = 0.053). The challenge induced marked inflammatory responses in the intestine and liver (assessed by lymphocyte counts, section area, goblet cell counts, and tissue architecture). Treatment was effective in improving inflammatory tissue signs such as lymphocyte infiltration in the cecum (P < 0.05), but not in the liver. The challenge with SE induced changes in all evaluated systems; however, intestinal integrity and some immune parameters were improved with the presence of the YCW.

这项研究的目的是评估在肠炎沙门氏菌（SE）攻击和酵母细胞壁（YCW）连续处理的肉鸡的免疫效果和肠道完整性的动态。孵化后4 d（感染后2 dpi [ dpi ]和治疗开始后），受攻击的动物的肠道通透性最高（P  <0.05）。非SE挑战组的循环白细胞数量最高（P  <0.005）。尽管如此，受到挑战的肉鸡始终呈现出更高数量的各种细胞亚型，尤其是在14 D时（Kul01 ^- MHC II类⁺，Kul01 ⁺ MHC II类）⁺，Kul01 ⁺ MHC II类^-细胞，以及串联的CD4 ⁺和CD8 ⁺细胞）。治疗有效地避免了总白细胞的减少，并防止了由激发引起的一些免疫亚群的波动，例如针对Kul01 ^- MHC II ⁺和CD8 ⁺细胞。在6 dpi攻击后吞噬细胞数量增加，而YCW降低了这种效应（P  <0.05）。测试组呈现出最高数量的抗沙门氏菌IgA反应性动物，以及最高水平的IgA（P = 0.053）。挑战在肠道和肝脏引起明显的炎症反应（通过淋巴细胞计数，切片面积，杯状细胞计数和组织结构评估）。治疗可有效改善炎症性体征，例如盲肠中的淋巴细胞浸润（P  <0.05），但不能改善肝脏。SE的挑战引起了所有评估系统的变化；然而，YCW的存在改善了肠道完整性和一些免疫参数。