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首页> 外文期刊>Applied Microbiology >No Protective Effects of High-Dosage Dietary Zinc Oxide on Weaned Pigs Infected with Salmonella enterica Serovar Typhimurium DT104
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No Protective Effects of High-Dosage Dietary Zinc Oxide on Weaned Pigs Infected with Salmonella enterica Serovar Typhimurium DT104

机译：大剂量膳食氧化锌对断肠猪肠炎沙门氏菌鼠伤寒DT104感染的保护作用

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Twenty-eight-day-old weaned pigs were fed diets with a low (LZn), medium (MZn), or high (MZn) Zn concentration (50 to 80, 150, or 2,500 mg Zn/kg of diet, respectively) provided as zinc oxide (ZnO)(24 pigs per group). They were infected orally with Salmonella enterica serovar Typhimurium DT104 on day 32. Salmonellae were cultivated from feces (up to 42 days postinfection [dpi]) and organs (2 and 42 dpi). Activation of the adaptive systemic and mucosal immune systems was investigated by recording anti- Salmonella IgG levels and levels of B and T lymphocyte subpopulations in blood and gut-associated lymphatic tissue. Growth performance was recorded as well. Salmonellae were shed at higher levels and for longer periods in the HZn group ( P < 0.05), with no differences in the tissues. At 2 dpi, the relative percentages of CD4~(+) T helper cells ( P < 0.01) and of CD2~(+) T and NK cells ( P < 0.01) in blood were reduced from the relative cell counts obtained at 0 dpi, irrespective of the Zn group. The lowest percentage of cytotoxic T cells was found 14 dpi in the HZn group relative to the MZn ( P < 0.05) and LZn ( P < 0.01) groups. Supplementation of the feed with 2,500 mg Zn/kg of diet immediately after weaning could positively affect the immune responses of piglets infected with Salmonella Typhimurium, but for a short period only. After 2 weeks, all positive effects disappeared, and rather negative effects, such as higher shedding of salmonellae, lower T cell frequencies, and worse performance, occurred. Thus, supplementation with ZnO at high levels in the pig industry should be limited to 2 to 3 weeks.
机译：饲喂28日龄断奶仔猪的锌含量低（LZn），中等（MZn）或高（MZn）（分别为每公斤日粮50至80、150或2500 mg Zn）作为氧化锌（ZnO）（每组24头猪）。他们在第32天口服沙门氏沙门氏菌鼠伤寒DT104感染。沙门氏菌从粪便（感染后42天）和器官（2和42 dpi）培养。通过记录抗沙门氏菌IgG水平以及血液和肠道相关淋巴组织中B和T淋巴细胞亚群的水平，研究了适应性全身和粘膜免疫系统的激活。还记录了生长性能。在HZn组中，沙门氏菌的脱落水平较高且持续时间较长（P <0.05），而各组织之间无差异。在2 dpi时，血液中CD4〜（+）T辅助细胞的相对百分比（P <0.01）以及血液中CD2〜（+）T和NK细胞的相对百分比（P <0.01）从0 dpi获得的相对细胞计数降低，与Zn基团无关。在HZn组中，相对于MZn（P <0.05）和LZn（P <0.01）组，最低的细胞毒性T细胞百分比为14 dpi。断奶后立即向饲料中补充2,500 mg锌/ kg饲料可积极影响感染鼠伤寒沙门氏菌的仔猪的免疫反应，但仅在短时间内有效。 2周后，所有积极影响消失，而负面影响出现，例如沙门氏菌脱落增多，T细胞频率降低和性能下降。因此，在养猪业中以高水平添加ZnO的时间应限制为2至3周。

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