复合益生菌对肉仔鸡小肠形态和盲肠微生物菌群的影响

Effects of compound probiotics supplementation on small intestinal morphology and cecal microflora in broiler chicks

[目的]本试验旨在研究早期饲喂复合益生菌对肉仔鸡盲肠微生物组成、小肠上皮组织结构及紧密连接相关基因表达的影响。[方法]将144只1日龄健康青脚麻鸡随机分为3组,分别为对照组(CON)、低剂量(50 mg·d^-1)益生菌组(LP)和高剂量(100 mg·d^-1)益生菌组(HP),每组6个重复,每个重复8只鸡,从1日龄开始饮水中添加益生菌,试验期为2周。试验期间记录采食量和体重,于第14日龄采集小肠上皮组织,检测其形态结构及紧密连接相关基因表达,16S rRNA测序分析盲肠内容物微生物组成。[结果]试验期间HP组肉鸡体重高于对照组,但差异不显著(P>0.05)。与对照组相比,HP组肉鸡1~7日龄平均日采食量显著降低(P<0.05),但7~14日龄平均日采食量有升高的趋势(P>0.05);HP组肉鸡1~7日龄料重比极显著低于CON组(P<0.01)。LP组与CON组之间以上指标均无显著差异(P>0.05)。与CON组相比,添加益生菌显著降低隐窝深度,增加绒毛高度及绒毛高度与隐窝深度的比值;HP组回肠和盲肠上皮闭锁小带蛋白1基因(ZO 1)和回肠上皮闭合蛋白基因(OCLN)表达显著上调(P<0.05);LP组盲肠上皮黏蛋白2基因(MUC 2)表达显著上调(P<0.05)。16S rRNA高通量测序结果表明,与CON组相比,早期饲喂复合益生菌对肉鸡盲肠内容物中细菌多样性无显著影响(P>0.05),但LP组盲肠中Sellimonas和Intestinimonas属的丰度显著增加(P<0.05),HP组Akkermansiaceae科的丰度极显著增加(P<0.01)。[结论]早期饲喂复合益生菌对肉仔鸡盲肠内容物中细菌多样性无显著影响,但可升高某些有益菌的定殖丰度;上调小肠上皮组织中紧密连接相关基因的表达,促进绒毛生长,从而潜在影响肉鸡早期和后期的生长性能。

[Objectives]This study was conducted to elucidate the effects of compound probiotics supplementation on small intestinal morphology,tight junction(TJ)-related genes expression and cecum microflora composition in chicks.[Methods]One hundred and forty four one-day-old green-legged chicks were randomly assigned to three groups with six replicates of broiler chicks.There were control(CON),low-dose(50 mg·d^-1)probiotics(LP)and high dose(100 mg·d^-1)probiotics(HP)groups,respectively.Probiotics were added by drinking water for two weeks from hatching.Feed intake and body weight were recorded during the whole experiment.Animals were slaughtered,and samples were collected at 14 days of age.Morphological structures and intestinal tight junction-related genes expression in small intestine were detected,and cecum microflora composition was analyzed by 16S rRNA sequencing.[Results]Compared to CON group,chickens in HP group showed a significant decrease of average daily feed intake(ADFI)and feed conversion ratio(FCR)from 1 to 7 days(P<0.01),and a tendency increase of feed intake from 7-14 days(P>0.05).Probiotics treatment significantly decreased crypt depth,increased villus height and the ratio of villus height to crypt depth in the intestine.Compared to CON group,HP group showed higher level of zonula occludens-1(ZO 1)mRNA expression in the ileum and cecum,and occludin(OCLN)mRNA expression in ileum;LP group exhibited higher level of mucin 2(MUC 2)mRNA expression in the cecum.16S high-throughput sequencing results showed that probiotics had no significant effect on the diversity of cecal microflora;however,LP administration significantly increased(P<0.05)the abundance of the genus Sellimonas and Intestinimonas,and HP administration significantly increased(P<0.01)the abundance of family Akkermansiaceae by Metastat analysis.[Conclusions]In conclusion,the supplementation of probiotics during early development can promote the development of small intestinal villi,increase tight junction-related genes expression level,and increase the colonization of beneficial bacteria in cecum,which will finally lead to a potential impact on promoting growth performance in broiler chicks.