【作者】 龚敏；

【导师】 印遇龙；

【作者基本信息】 南昌大学 ， 食品科学与工程， 2011， 博士

【摘要】 随着玉米供应的日趋紧张,开发新的饲料原料已成为发展养殖业的一个首要问题。麦类饲粮,尤其是小麦,因其产量多,价格低,已经被列为代替玉米的重要对象。但是,到目前为止,麦类饲粮还不能广泛应用,这是因为其中广泛存在一种抗营养因子---非淀粉多糖。非淀粉多糖是植物组织中除淀粉以外的所有碳水化合物的总称,它们的特殊结构使它们具有一定的抗营养特性,相应的非淀粉多糖酶制剂可以破坏其特殊结构,从而去除或降低其抗营养作用,提高饲料的利用效率和改善动物的生产性能。本研究通过体外模拟试验确定小麦日粮中添加阿拉伯木聚糖酶的最适含量,通过动物试验研究日粮添加阿拉伯木聚糖酶对断奶仔猪肠道菌群区系及糖转运载体的影响,为研制和开发无抗生素和激素的新型饲料资源和绿色饲料添加剂提供理论依据,从基因水平揭示木聚糖酶的作用机理。本研究主要内容：用气相色谱法测定小麦中非淀粉多糖的含量,通过体外模拟试验确定阿拉伯木聚糖酶对小麦日粮的最佳降解酶浓度；研究小麦日粮添加不同酶含量及日龄对断奶仔猪生长性能,血清糖、脂、蛋白质,血清游离氨基酸等相关指标的影响；通过肠道形态学指标的变化,肠道菌群区系的变化,肠道糖转运载体SGLT1mRNA表达量的变化,探索阿拉伯木聚糖酶的作用机理。主要研究结果如下：(1)小麦非淀粉多糖主要由鼠李糖、阿拉伯糖、木糖、甘露聚糖、半乳糖、葡萄糖等单糖构成；添加阿拉伯木聚糖酶对可溶非淀粉多糖的降解效果比不可溶非淀粉多糖的降解效果显著；不管是可溶还是不可溶非淀粉多糖,其中对阿拉伯糖、木糖的降解效果显著；在酶水平为60000IU/g小麦时,降解效果最大。(2)木聚糖酶水平与小麦可溶非淀粉多糖、不可溶非淀粉多糖、总非淀粉多糖含量呈显著或极显著的二次或三次回归关系；以可溶非淀粉多糖、不可溶非淀粉多糖、总非淀粉多糖含量变化为指标,每千克小麦的适宜木聚糖酶添加量分别为0.718g、0.732g、0.717g。(3)酶制剂的添加存在剂量效应关系,小麦日粮作为NSP酶的作用底物,只有在日粮营养水平达到基本要求并保持适宜的比例关系时,NSP酶才能表现出最佳效能；而且随着日龄的增加,小麦日粮添加木聚糖酶对生长性能的影响越来越明显。(4)小麦日粮添加阿拉伯木聚糖酶对断奶仔猪血清脂类代谢相关指标影响较大,而对血清糖、蛋白质、血清游离氨基酸等相关指标影响不大,日龄对个别血清氨基酸含量有一定的影响。(5)小麦基础日粮组空肠中段绒毛长度、隐窝深度、绒毛长度／隐窝深度值均高于添加不同酶含量组,提示日粮中非淀粉多糖含量与营养物质的吸收有一定的关系,非淀粉多糖含量越高可能刺激小肠粘膜结构发生适应性改变。(6)小麦非淀粉多糖含量对断奶仔猪回肠、结肠、盲肠微生物(双歧杆菌、乳酸杆菌、大肠杆菌、链球菌)的数量影响不大,各组间均无显著性差异(P>0.05)；’但小麦日粮添加适宜的木聚糖酶可使肠道有益菌数量(双歧杆菌、乳酸杆菌)表现出增加趋势,有害菌数量(大肠杆菌、链球菌)表现出减少趋势,提示添加适宜的外源酶制剂可改变肠道微生物种群,从而改善仔猪的生长性能,减少腹泻发生率(7)小麦日粮添加不同含量阿拉伯木聚糖酶可上调断奶仔猪空肠中段、回肠中段钠／葡萄糖共转运载体—1mRNA的表达量,但并无显著性差异(P>0.05)；提示小麦日粮添加阿拉伯木聚糖酶可提高葡萄糖的吸收,而且SGLT1mRNA的表达与葡萄糖吸收和生产性能之间具有密切关系。但SGLT1mRNA的表达受多种因素的影响,其在转录水平和转录后水平的表达及其表达的调节,尚有待于进一步地深入研究。更多还原

【Abstract】 With increasingly supplies of corn, the development of new feed ingredients has become a priority in the development of aquaculture issues. Wheat diet, particularly wheat, because of its yield, low prices, has been listed as an important object instead of corn. However, wheat can not be widely used in the stocking raising now because there is a wide range of anti-nutritional factors --- non-starch polysaccharides. Non-starch polysaccharides in plant tissues is the general term for all the carbohydrates in addition to starch, and they have some anti-nutritional characteristics because of their special structure, but the corresponding non-starch polysaccharides enzymes can destroy the special structure, which remove or reduce the anti-nutritional characteristics, and improve feed efficiency and improve animal performance. The aim of this study was to determine the optimum xylanase supplementation concentration in wheat by vitro testing, and reveal the mechanism which non-starch polysaccharides in wheat effect intestinal microflora and sodium/glucose cotransporters in weaned piglets.Major content of this study:determine the non-starch polysaccharides contents in wheat by gas chromatography; determine the optimum xylanase Supplementation concentration in wheat by vitro testing; study the effect of wheat diet supplemented with different enzyme content in the different age on growth performance, serum glucose and lipids, protein, serum free amino acid and other related indexes; reveal the mechanism which non-starch polysaccharides in wheat effect intestinal microflora and sodium/glucose cotransporters in weaned piglets by the indexes of intestinal tract morphology and intestinal glucose transporter (SGLT1mRNA) expression. The main results are as follows:(1)Non-starch polysaccharides of wheat mainly comprise of rhamnose, arabinose,xylose,mannose, galactose, glucose and other monosaccharides. There are more degradation of soluble non-starch polysaccharides than insoluble non-starch polysaccharides in the wheat diet of xylanase Supplementation. Either soluble or insoluble non-starch polysaccharides, the arabinose, xylose degradation is remarkable. There is significantly effect of xylanas Supplementation on NSP of wheat while the xylanase level is 60000IU/g.(2)There are significant or highly significant regression relationship between the xylanase level and the contents of SNSP、NSP、NSP. The appropriate xylanase levels for SNSP、INSP、NSP were respectively 0.718g、0.732g/k、0.717g/kg.(3)There is dose-response relationship between xylanase supplementation concentration and wheat diet. While the nutrient levels in the diet can meet the basic requirements of piglets, the effect of optimum xylanase supplementation on the performance of piglets is the best. With the increase of age, the effect on the performance of piglets is more and more evident.(4)There are more effect on the related indexes about serum lipids metabolism, but there is little effect on the related indexes about serum glucose, protein, serum free amino acid.(5)Middle jejunum villi length, crypt depth, villous length/crypt depth of diet group based wheat were higher than that of diets groups supplemented xylanase. It is suggested that there a certain relationship between the content of non-starch polysaccharides in the wheat diets and nutrient absorption, the higher content of non-starch polysaccharides may stimulate adaptive changes in the structure of the small intestinal mucosa.(6)There is little effect of non-starch polysaccharides content on the number of ileum, colon, cecum microorganisms (Bifidobacterium, Lactobacillus, Escherichia coli, Streptococcus) of weaned piglets. There is no significant difference (P> 0.05) between each group, but it showed an upward trend in the number of intestinal bacteria (Bifidobacterium, Lactobacillus) of wheat diet groups supplemented xylanase, it showed a decreasing trend in the number of harmful bacteria (E.coli, Streptococcus). It is suggested that exogenous enzymes can change the intestinal microbial populations, thereby improve the growth performance of pigs to reduce the incidence of diarrhea.(7)Wheat diet supplemented xylanase could increase the absorption of glucose, the expression of SGLT1mRNA, there is a close relationship between the uptake of SGLT1mRNA and the growth performance. But SGLT1mRNA expression is regulated by many factors, the level of transcription and post-transcriptional regulation of its expression, still needs further in-depth study.更多还原