共查询到20条相似文献，搜索用时 78 毫秒
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白腐真菌对稻草中木质素、纤维素降解的影响 总被引：5，自引：0，他引：5
在我国可用作饲料的农作物秸秆有多种,但具有共同营养的特点:蛋白质、可溶性碳水化合物、矿物质和胡萝卜素含量低,而粗纤维含量高。有关秸秆处理的方法有多种,微生物处理秸秆是人们最早应用秸秆作为饲料的方法之一,它与物理、化学等方法处理相比,具有投资少,操作简单,不污染环境等优点。秸秆的粗纤维包括纤维素、半纤维素和木质素,其中纤维素和半纤维素能够被草食动物的瘤胃微生物充分降解利用,但由于木质素和纤维素之间镶嵌在一起形成坚固的酯键,阻碍了瘤胃微生物及单胃动物对纤维素的降解,导致秸秆消化率低。因此提高秸秆的消化率的关键是… 相似文献
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农作物秸秆中的纤维素、半纤维素、木质素是世界上最丰富的碳水化合物资源,其中纤维素和半纤维素能够被草食动物瘤胃微生物降解利用,但由于木质素与纤维素和半纤维素紧密结合,镶嵌形成酯键,从而阻碍了瘤胃微生物及单胃动物对秸秆中纤维素和半纤维素的利用,因此提高秸秆消化率的关键是对木质素的降解。如何利用微生物降解木质纤维素,生物学家进行了大量的研究,尤其在瘤胃微生物方面的研究,取得了重大进展。1971年Kirk.T.K发现某些真菌有降解木质素的能力,尤其是白腐真菌能彻底降解天然植物中的纤维素和木质素复合物,氧化成二氧化碳和水,这引起国际科学界和工业界的极大兴趣。 相似文献
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氨化处理对秸秆理化特性和组织特性的影响 总被引：2，自引：0，他引：2
1 秸秆氨化的原理1 1 碱化作用 秸秆中碳水化合物含量丰富 ,但绝大部分是细胞壁构成成分 ,如纤维素、半纤维素、木质素和角质等 ,木质素和角质等不能消化 ,它们坚固地镶嵌在纤维素中 ,并且紧密相连 ,形成木质化和结晶化 ,妨碍动物消化分解。碱类物质中氢氧根能使饲料纤维内部的氢键结合变弱 ,导致纤维分子膨胀 ,而且能溶解半纤维素 ,皂化糖醛酸和乙酸的酯键 ,中和游离的糖醛酸 ,削弱纤维素与木质素之间的联系 ,这样就使反刍动物瘤胃微生物更易利用。因此 ,通过碱化作用能使纤维素、半纤维素与木质素部分分解 ,打断纤维素、半纤维素与木… 相似文献
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如何充分科学地利用好秸秆资源,变废为宝,成为农村面临的重大问题.秸秆类饲料的营养特点是粗纤维含量高、消化率低.纤维素和半纤维素是植物细胞壁（如小麦秸、玉米秸、稻草秸、大豆秸、花生秸、甘蔗渣和橘子渣）的主要成分,与木质素交织在一起很难被反刍动物瘤胃微生物完全降解,增加纤维素和半纤维素的降解率可潜在的提高动物的生产性能.酶制剂作为新一代饲料添加剂在畜牧业中的应用越来越普遍.人们根据酶能促进蛋白质、脂肪、淀粉、粗纤维分解的作用,深入研究找到一种能补充瘤胃微生物消化能力的物质—外源性酶制剂,来提高饲料利用率和改善奶牛生产性能. 相似文献
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<正>1菌糠的用途菌糠的原料基质中或因蛋白质含量较低,或因粗纤维含量过高,导致了其可饲用性能较差,严重制约了动物对营养物质的消化吸收率和适口性,所以很少或根本不作为畜禽饲料,但经过多种微生物的发酵作用,纤维素、半纤维素和木质素等均被不同程度的降解,同 相似文献
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《北方牧业(奶牛)》2006,(12):27-27
奶牛主要以粗纤维含量较高的植物茎叶等粗饲料为主要饲料．通过瘤胃微生物发酵产生的纤维素酶将纤维素降解为易吸收的低分子糖，但是由于瘤胃微生物产生的纤维素酶是有限的，外源补充可提高瘤胃中纤维素酶含量，达到提高降解纤维素的目的．有试验证明，在奶牛饲粮中添加酶制剂尤其是纤维素酶可明显提高饲粮中粗纤维的利用率。在奶牛饲粮中添加真菌纤维素酶，可使泌乳量提高17．5％，饲料利用率提高14．5％。日粮中粗纤维水平与瘤胃液中乙酸和丙酸的比例呈线性相关。高纤维日粮促进乙酸的生成．而低纤维日粮则促进丙酸的生成。因此乳脂含量高的牛乳，对应的奶牛日粮中纤维索的含量也高。在奶牛等反刍动物营养上，传统的观念认为。饲料中不必添加纤维素酶和其他饲用酶制剂。这种观点认为．反刍动物瘤胃内和肠道中存在大量的微生物．这些微生物足以完全降解饲料中的纤维素。但最新的研究结果以及在实际生产中Ⅲ现的问题对这一观点提卅了异议。研究发现，在日粮中添加纤维素酶能提高奶牛的生产性能。这表明，目前高产奶牛胃肠道中微生物可能不足以降解高纤维日粮中的纤维素，从而使得奶牛不能达到最佳生产性能。 相似文献
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瘤胃微生物、饲料特性以及动物饲喂方式等都能够影响反刍动物对纤维素的消化,日粮中纤维的降解程度和降解速度主要取决于微生物与饲料纤维发酵基质的接触程度。文中就瘤胃微生物和动物自身对纤维降解的影响进行了讨论。 相似文献
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与单胃动物相比 ,反刍动物具有较强的降解、消化饲料的能力 ,这与其体内的瘤胃微生物密切相关。瘤胃微生物包括细菌、原虫和真菌。1 瘤胃微生物的特点1 1 瘤胃中的细菌 反刍动物是食草动物 ,在其食物中含有大量的纤维素 ,少量木质素和多糖类、蛋白质等复杂大分子物 ,因此在瘤胃中发育有能降解这些复杂有机物的微生物区系。1 1 1 分解纤维菌 瘤胃中能分解纤维素的细菌十分丰富 ,主要有产琥珀酸拟杆菌、白色瘤胃球菌、生黄瘤胃球菌和溶纤维丁酸弧菌 ,还有锁头状丁酸弧菌。其中对纤维分解起主要作用的细菌是产琥珀酸拟杆菌、白色瘤胃球… 相似文献
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魏静 《四川畜牧兽医学院学报》2009,(4):28-32
在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。 相似文献
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本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。 相似文献
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REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air. 相似文献
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Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF
Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo. 相似文献
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以国际标准强毒Ｒ株人工感染非免疫产蛋鸡,定时扑杀,分别从鼻窦、眶下孔、气管、肺、气囊、卵巢和输卵管分离ＭＧ,并收集感染鸡所产蛋分离ＭＧ。结果表明,人工感染４８小时后上、下呼吸道及肺已被全面感染,９６小时气囊已被感染,１２０小时输卵管已能分离到ＭＧ,卵巢始终分离不到ＭＧ。人工感染鸡自１４４小时便能在其所产蛋中分离出ＭＧ。药物治疗能在７２小时内消除感染,油乳剂苗则需２４天后逐渐降低蛋内ＭＧ分离率,药物卵内注射、种蛋药浴、高温处理均能杀死卵内ＭＧ,但以研制的种蛋浸泡剂药浴效果为最好。 相似文献