不同来源木聚糖酶对黄羽肉鸡小肠绒毛形态结构和黏膜生长抑素mRNA表达的影响

Effects of Different Sources of Xylanases on Villus Morphology and Intestinal Somatostatin mRNA Expression in Yellow-feathered Broilers

本文旨在比较研究小麦型饲粮中添加不同来源木聚糖酶对黄羽肉鸡小肠绒毛形态结构和黏膜生长抑素(SS)mRNA表达的影响。选择22日龄、体重相近的健康黄羽肉鸡375羽,随机分成3个组,每组5个重复,每重复25羽。对照组饲喂小麦型基础饲粮,试验Ⅰ和Ⅱ组分别饲喂在基础日粮中添加250mL/t真菌性和细菌性木聚糖酶的试验饲粮,试验期为28d,制作石腊切片观察小肠形态学结构,并采用相对定量RT-PCR方法测定十二指肠和空肠黏膜SS mRNA的表达。结果表明,在小麦基础饲粮中添加木聚糖酶:1)十二指肠、空肠和回肠绒毛高度均呈试验Ⅱ组>试验Ⅰ组>对照组的趋势。但除试验Ⅱ组十二指肠绒毛高度显著高于对照组外(P<0.05),各组间其余肠段绒毛高度差异不显著(P>0.05)。2)十二指肠、空肠和回肠隐窝深度均呈试验Ⅱ组<试验Ⅰ组<对照组的趋势。与对照组相比,试验Ⅰ组十二指肠隐窝深度降低了11.39%(P<0.05),而试验Ⅱ组十二指肠和空肠隐窝深度分别降低了17.90%(P<0.01)和15.61%(P<0.05),回肠隐窝深度各组间差异不显著(P>0.05)。3)十二指肠、空肠和回肠绒毛高度/隐窝深度(V/C)值均表现出试验Ⅱ组>试验Ⅰ组>对照组的规律。其中,试验Ⅰ组十二指肠V/C值比对照组高21.94%(P<0.05),试验Ⅱ组3个肠段V/C值分别比对照组高38.66%(P<0.01)、37.83%(P<0.01)和25.58%(P<0.05),且试验Ⅱ组十二指肠V/C值也比试验Ⅰ组高出14.41%(P<0.05)。4)试验Ⅰ组和Ⅱ组试鸡十二指肠SS mRNA的表达量分别比对照组降低了49.59%(P<0.01)和52.49%(P<0.01),空肠SS mRNA表达量分别下降了6.83%(P>0.05)和44.30%(P<0.05),但2个试验组间差异不显著(P>0.05)。由此可知,小麦型饲粮中添加2种来源的木聚糖酶均可促进黄羽肉鸡小肠绒毛形态发育,抑制肠黏膜SS mRNA的表达,总体上细菌性木聚糖酶的作用效果与真菌性木聚糖酶没有显著差异。

This experiment was conducted to investigate and compare the effects of bacterial xylanase and fungal xylanase on villus morphology and intestinal somatostatin（SS） mRNA expression in yellow-feathered broilers.Three hundred and seventy-five 22-day-old in yellow-feathered broilers were randomly assigned to three groups with five replicates and twenty-five chicks in each pen.Broilers in three groups were fed diets supplemented with 0（control group）,250 mL/t fungal xylanase（Exp Ⅰ） and 250 mL/t bacterial xylanase（Exp Ⅱ） in wheat-based diet.The experiment lasted for 28 days.Sample paraffin section staining method was adopted to observe the morphological structure of small intestine,and the expression of SS mRNA in duodenal and jejunal mucosa was measured by relative quantitative RT-PCR method.The results showed as follows： 1） the villus height of duodenum,jejunum and ileum showed a trend as Exp ⅡExp Ⅰcontrol group.The villus height of duodenum in Exp Ⅱ was higher than that in control group（P0.05）,the villus height of other intestinal sections among the three groups were not significantly different（P0.05）.2） The crypt depth of duodenum,jejunum and ileum showed a trend as Exp ⅡExp Ⅰcontrol group.Compared with control group,the crypt depth of duodenum in Exp Ⅰ was decreased by 11.39%（P0.05）,and the crypt depths of duodenum and jejunum in Exp Ⅱ were reduced by 17.90%（P0.01） and 15.61%（P0.05）,respectively,but the crypt depth of ileum among the three groups were not significantly different（P0.05）.3） The villus height/crypt depth（V/C） ratio of duodenum,jejunum and ileum showed a pattern as Exp ⅡExp Ⅰcontrol group.Compared with control group,V/C ratio of duodenum in Exp Ⅰ was increased by 21.94%（P0.05）,and V/C ratios of duodenum,jejunum and ileum in Exp Ⅱ were increased by 38.66%（P0.01）,37.83%（P0.01） and 25.58%（P0.05）,respectively.Furthermore,V/C ratio of duodenum in Exp Ⅱ was 14.41% higher than that in Exp Ⅰ（P0.05）.4） Compared with control group,expression of SS mRNA of duodenum and jejunum mucosa in Exp I and Exp Ⅱ was reduced by 49.59%（P0.01） and 52.49%（P0.01）,6.83%（P0.05） and 44.30%（P0.05）,respectively,but there was no difference between them（P0.05）.These results indicate that the supplementation of either fungal xylanase or bacterial xylanase in wheat-based diet can improve the small intestinal villus morphological development in difference degrees,and inhabit the expression of SS mRNA of intestnal mucosa in yellow feathered broilers.The effects of bacterial xylanase is equal to fungal xylanase.