屎肠球菌对感染柔嫩艾美耳球虫肉鸡生长性能和肠道屏障的影响

Effect of Enterococcus faecium on Growth Performance and Intestinal Barrier of Broilers Infected with Eimeria tenella

旨在探究屎肠球菌(Enterococcus faecium)对人工感染柔嫩艾美耳球虫(Eimeria tenella)肉鸡生长性能、存活率、盲肠损伤、粪便卵囊排出和肠道屏障功能的影响。选取体重相近的1日龄肉鸡(罗斯308)180羽,随机分为5组,包括空白对照组(NC)、感染对照组(PC)、70 mg·kg^(-1)盐霉素添加组(SAL)、E.faecium 1.0×10^(8) CFU·kg^(-1)添加组(EA)和E.faecium 2.5×10^(9)CFU·kg^(-1)添加组(EB)。NC和PC组饲喂基础饲粮,SAL、EA、EB组在分组后即开始饲喂添加盐霉素和E.faecium的饲粮,持续至试验结束。在15 d时,除NC组外所有试验组的鸡均口服感染1.0×10^(5)个E.tenella孢子化卵囊。通过分析平均日增重(ADG)、克粪便卵囊数(OPG)、盲肠损伤评分、组织病理学检查和盲肠屏障相关分子(iNOS、MUC2、Occludin、JAM2、ZO-1)的基因表达量来评价E.faecium的抗球虫效果。结果表明:1)相比于NC组,EA和EB组可以显著增加感染前ADG(P<0.05),并且感染后SAL和EB组ADG显著高于PC组(P<0.05);2)SAL、EA和EB组粪便中的卵囊数显著低于PC组(P<0.05),PC组可以观察到明显的病理损伤、炎性细胞浸润和肠绒毛断裂,而预防组(SAL、EA、EB)病变较轻微,但是所有感染组盲肠损伤评分并没有差异(P>0.05);3)在整个试验期间各组存活率分别为100%(NC)、58.33%(PC)、83.33%(SAL)、58.33%(EA)、75.00%(EB);4)相比于NC组,PC组肠道iNOS、MUC2、Occludin、JAM2和ZO-1的表达均显著下降(P<0.05),而SAL、EA、EB组均能显著提高iNOS的表达量(P<0.05);EB组肠道MUC2、Occludin和JAM2的表达量也显著高于PC组(P<0.05)。综上所述,E.faecium具有一定的抗球虫效果,可能通过调节肠道屏障相关分子的表达发挥作用。

The present study was designed to evaluate the effect of dietary supplementation with Enterococcus faecium on growth performance,survival rate,caecal lesion,fecal oocyst excretion and intestinal barrier in broiler chickens challenged with E.tenella infection.Total of 180 one-day-old broiler chickens(Ross 308)with similar body weight were randomly distributed into 5 groups,including control group(NC),positive group(PC),salinomycin group(SAL),E.faecium group(EA and EB).Chickens in NC and PC groups were fed with basal diet,while SAL,EA,EB groups were fed with the diet supplemented with 70 mg·kg^(-1) salinomycin,1.0×10^(8) CFU·kg^(-1) E.faecium and 2.5×10^(9) CFU·kg^(-1) E.faecium,respectively,until the end of the experiment.At 15 days of age,the chickens in all groups except NC were orally infected with 1.0×10^(5) sporulated E.tenella oocysts.Then,the anticoccidial efficacy of dietary supplementation with E.faecium was evaluated by the average daily gain(ADG),oocyst per gram faeces(OPG),caecal lesion score,histopathological examinations and gene expression levels of cecal barrier related molecules(iNOS,MUC2,Occludin,JAM2,ZO-1).The results showed that:1)Compared with NC group,ADG was significantly increased in EA and EB groups before treated with E.tenella(P<0.05).The ADG of SAL and EB groups were higher than that in PC group after infected with E.tenella(P<0.05).2)Compared with PC group,the OPG in all pre-treated groups(SAL,EA,and EB)were significantly reduced(P<0.05).Besides,the obvious pathological damage with immune cell infiltration and villi blunting was observed in the cecum in PC group compared with pre-treated groups,while no significant difference was found in all pre-treated groups regard to the lesion score(P>0.05).3)During the whole test period,the survival rates of NC,PC,SAL,EA and EB groups were 100%,58.33%,83.33%,58.33%and 75.00%,respectively.4)Compared with NC group,the expression of iNOS,MUC2,Occludin,JAM2,ZO-1 in PC group was significantly decreased(P<0.05).The expression of iNOS in all pre-treated groups and MUC2,Occludin,JAM2 in EB group showed a remarkable increase compared with PC group(P<0.05).In conclusion,the results of this study are promising and indicate many beneficial effects of E.faecium-supplementation in poultry diets to reduce the negative consequences of E.tenella disease by regulating gene expression of intestinal barrier related molecules.