代乳粉添加单宁酸对7—28日龄湖羊羔羊胃肠道发育的影响

Effects of Tannic Acid Addition in Milk Replacer on Development of Gastrointestinal Tract of 7 to 28 Days Old Hu Lambs

【目的】观察代乳粉中添加单宁酸对7—28日龄湖羊羔羊胃肠道生长发育的影响。【方法】选择同质性好的7日龄湖羊公羔(双羔)30只,随机分为2组,每组15只,每只1个重复,分别饲喂对照代乳粉或单宁酸含量为0.2%的代乳粉,试验期21 d。羔羊28日龄时饲养试验结束,每组随机选择8只羔羊进行屠宰,分离胃室和肠段,分别称量各胃室和各肠段净质量以及含内容物质量,并量取各肠段的长度,计算各胃室和各肠段的相对质量和相对长度及内容物分布。肠道组织形态学和上皮细胞凋亡率用皱胃胃底腺区及十二指肠、空肠和回肠中段的组织样品测定。肠道屏障功能相关的闭锁蛋白(occludin)、闭锁小带1(zonula occludens-1,ZO-1)和紧密连接蛋白1(claudin 1)mRNA表达量用采集的十二指肠、空肠和回肠黏膜测定。【结果】除十二指肠指数(%活体质量,P=0.012)和相对质量(%全肠质量,P=0.034;%全胃肠质量,P=0.017)、空肠和结肠相对长度(%全肠长度,P=0.030,P=0.004)及结肠内容物分布(%活体质量,P=0.039)外,单宁酸对羔羊胃肠指数(%活体质量)、胃肠相对质量(%全胃质量、%全肠质量和%全胃肠质量)、肠道相对长度(%全肠长度)、内容物相对质量(%活体质量)、胃肠内容物相对总胃/肠内容物及总胃肠内容物相对质量(%总胃内容物、总肠内容物、总胃肠内容物)以及小肠claudin 1蛋白mRNA表达量均没有产生显著影响(P>0.05),但显著提高羔羊十二指肠肌层厚度并降低绒毛宽度(P=0.013,P=0.001),显著上调空肠ZO-1蛋白mRNA表达量(P=0.003),此外,单宁酸有上调羔羊空肠occludin蛋白mRNA表达量并降低空肠绒毛宽度和隐窝深度以及空肠和回肠上皮细胞凋亡率的趋势(P=0.077,P=0.073,P=0.062,P=0.097,P=0.052)。【结论】单宁酸显著降低7—28日龄湖羊羔羊十二指肠相对质量和空肠相对长度,但可通过提高十二指肠肌层厚度、上调空肠ZO-1蛋白和occludin蛋白mRNA表达量并降低空肠隐窝深度及空肠和回肠上皮细胞凋亡率来改善肠屏障功能。

【Objective】This study was conducted to investigate the effects of tannic acid supplementation to milk replacer on the development of gastrointestinal tract of 7 to 28 day-old Hu lambs.【Method】Thirty 7 day-old Hu male lambs were chosen and divided into 2 groups,fifteen lambs in each group and each lamb as a duplication.Lambs were fed milk replacer with or without 0.2%tannic acid,respectively.The test lasted 21 days.Eight lambs were selected from each group randomly and slaughtered at 28 day-old.The weights of the compound stomach and the intestinal tract with and without content,and lengths of the intestinal tract were measured,then the relative quality and length were calculated.While the tissue samples from fundus gland region of the abomasum,the middle part of duodenum,jejunum and ileum were fixed in paraformaldehyde to analyse the histomorphology,and the apoptotic rate of intestinal epithelial cells as well.And the mRNA expression of occludin,ZO-1 and claudin 1 protein of duodenum,jejunum and ileum mucosa were measured.【Result】The results showed that except relative weights of duodenum(%body weight,P=0.012;%intestinal tract weight,P=0.034;%gastrointestinal tract weight,P=0.017),relative length of jejunum and colon(%intestinal tract length,P=0.030,P=0.004),and content of colon(%body weight,P=0.039),the relative weights(%body weight,%stomach weight,%intestinal tract weight,and%gastrointestinal tract weight),relative lengths(%intestinal tract length),content of stomach and intestinal tract(%body weight,%stomach content weight,%intestinal tract content weight,and%gastrointestinal tract content weight),and mRNA expression of claudin 1 protein in intestinal tract of lambs were not affected by tannic acid(P>0.05).However,tannic acid elongated the muscular thickness of duodenum and decreased the villus width of lamb duodenum significantly(P=0.013,P=0.001),and up-regulated mRNA expression of ZO-1 protein of jejunum(P=0.003).And there was a tendency that tannic acid up-regulated mRNA expression of occludin protein of jejunum(P=0.077),and decreased villus width and crypt depth of jejunum and the apoptotic rate of jejunum and ileum cells(P=0.073,P=0.062,P=0.097,P=0.052).【Conclusion】In conclusion,tannic acid decreased the relative weights of duodenum and relative length of jejunum of 7-28 day-old Hu lambs,but improved the barrier function of intestinal tract via elongating the muscular thickness of duodenum,up-regulating the mRNA expression of ZO-1 and occludin protein of jejunum,and decreasing the crypt depth of jejunum and the apoptotic rate of jejunum and ileum cells.