高锌日粮对断奶仔猪肠道黏膜免疫及黏膜上皮形态的影响

Effect of high-level zinc diets on intestinal mucosal immunity and morphology of weanling piglets

本试验旨在研究长期饲喂不同锌源的高锌日粮对断奶应激仔猪肠道黏膜免疫及黏膜上皮形态的影响。选用临床检查健康的(26±2)日龄"杜×长×大"三元杂交断奶仔猪60头,按体质量和性别随机分成3组,每组20头,分别饲喂基础日粮、基础日粮+3 000 mg.kg-1氧化锌和基础日粮+500 mg.kg-1蛋氨酸锌。试验期70 d。于试验结束时,每组选取5头仔猪放血致死,分别取十二指肠近端、空肠近端1/4处、空肠远端1/4处和回肠中段,用于测定肠黏膜绒毛高度、绒毛宽度、隐窝深度,小肠上皮间淋巴细胞、杯状细胞数量,粘液层厚度及肠道粘液中IgA的含量。结果显示,在断奶后0～42 d,添加高锌日粮组仔猪的体重和日增重显著或极显著高于对照组仔猪(P<0.05或P<0.01),而在断奶后42～70 d,对照组仔猪日增重显著高于添加高锌日粮组仔猪(P<0.05);两高锌组仔猪小肠黏膜结构有明显的损伤,表现为绒毛高度下降,隐窝变深,肠黏膜上皮细胞萎缩,肠道粘液层厚度变薄;上皮间淋巴细胞数、杯状细胞数和肠道黏液中IgA水平都显著或极显著低于对照组(P<0.05或P<0.01)。高锌日粮长期暴露引起断奶仔猪锌中毒,改变了肠道黏膜上皮结构的完整性,并降低了仔猪生长性能及肠道黏膜免疫功能。

The purpose of this experiment was to study the effects of different kinds of high-level zinc diets on intestinal mucosal immunity and morphology of weanling piglets.Sixty（26±2） d of age ＂Duroc × Landrace × Yorkshire＂ crossbred weanling piglets were randomly divided into 3 groups of 20 piglets each by weight and sex,which were fed a basal diet with 3 000 mg·kg-1 zinc（from ZnO） or 500 mg·kg-1 zinc（from Zn-Met）,respectively.The trial was conducted for 70 d.At the end of the trial,15 piglets（5 per Group） were bled via the anterior vena cava.The proximal duodenum,1/4 proximal jejunum,1/4 distal jejunum and middle ileum were collected for measuring the structure of mucosal epithelium,the number of intraepithelial lymphocyte and the goblet cells,the level of IgA and the thickness of slime layer in small intestine.The results indicated that the average weight and daily gain of Group II and III were higher than those of the control group on d 0-42 postweaned（P0.01 or P0.05）,but the average daily gain of the control group was higher than that of Group Ⅱ and Ⅲ on d 42-70 postweaned（P0.05）;the structure of small intestine mucous membrane was injured significantly in Group II and Group III,decreased villi height,deepened crypt,atrophied and shed mucosa epithelia,and thinningzed slime layer.The numbers of intraepithelial lymphocytes and the goblet cells and the level of IgA in Group II and Group III were lower than those of control group（P0.05 or P0.01）.The long-term exposure to high level zinc diets resulted in poisoning of weanling piglets,altered the structural integrality of intestine mucosa epithelia,and decreased growth performance and intestine mucosal immune function.