Liu Ping, Pieper Robert, Rieger Juliane, Vahjen Wilfried, Davin Roger, Plendl Johanna, Meyer Wilfried, Zentek Jürgen
Institute of Animal Nutrition, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
Institute of Veterinary Anatomy, Department of Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
PLoS One. 2014 Mar 7;9(3):e91091. doi: 10.1371/journal.pone.0091091. eCollection 2014.
The trace element zinc is often used in the diet of weaned piglets, as high doses have resulted in positive effects on intestinal health. However, the majority of previous studies evaluated zinc supplementations for a short period only and focused on the small intestine. The hypothesis of the present study was that low, medium and high levels of dietary zinc (57, 164 and 2,425 mg Zn/kg from zinc oxide) would affect colonic morphology and innate host defense mechanisms across 4 weeks post-weaning. Histological examinations were conducted regarding the colonic morphology and neutral, acidic, sialylated and sulphated mucins. The mRNA expression levels of mucin (MUC) 1, 2, 13, 20, toll-like receptor (TLR) 2, 4, interleukin (IL)-1β, 8, 10, interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) were also measured. The colonic crypt area increased in an age-depending manner, and the greatest area was found with medium concentration of dietary zinc. With the high concentration of dietary zinc, the number of goblet cells containing mixed neutral-acidic mucins and total mucins increased. Sialomucin containing goblet cells increased age-dependently. The expression of MUC2 increased with age and reached the highest level at 47 days of age. The expression levels of TLR2 and 4 decreased with age. The mRNA expression of TLR4 and the pro-inflammatory cytokine IL-8 were down-regulated with high dietary zinc treatment, while piglets fed with medium dietary zinc had the highest expression. It is concluded that dietary zinc level had a clear impact on colonic morphology, mucin profiles and immunological traits in piglets after weaning. Those changes might support local defense mechanisms and affect colonic physiology and contribute to the reported reduction of post-weaning diarrhea.
微量元素锌常用于断奶仔猪的日粮中，因为高剂量锌已被证明对肠道健康有积极影响。然而，之前的大多数研究仅在短时间内评估了锌的补充情况，并且主要关注小肠。本研究的假设是，低、中、高剂量的日粮锌（来自氧化锌的锌含量分别为57、164和2425毫克/千克）会在断奶后4周内影响结肠形态和宿主天然防御机制。对结肠形态以及中性、酸性、唾液酸化和硫酸化粘蛋白进行了组织学检查。还测量了粘蛋白（MUC）1、2、13、20、Toll样受体（TLR）2、4、白细胞介素（IL）-1β、8、10、干扰素-γ（IFN-γ）和转化生长因子-β（TGF-β）的mRNA表达水平。结肠隐窝面积随年龄增长而增加，日粮锌浓度为中等时隐窝面积最大。日粮锌浓度高时，含有混合中性-酸性粘蛋白和总粘蛋白的杯状细胞数量增加。含唾液酸粘蛋白的杯状细胞数量随年龄增长而增加。MUC2的表达随年龄增加而增加，并在47日龄时达到最高水平。TLR2和4的表达水平随年龄下降。高锌日粮处理使TLR4的mRNA表达和促炎细胞因子IL-8下调，而日粮锌浓度为中等的仔猪表达水平最高。研究得出结论，日粮锌水平对断奶后仔猪的结肠形态、粘蛋白谱和免疫特性有明显影响。这些变化可能支持局部防御机制，并影响结肠生理功能，有助于减少断奶后腹泻的发生。
