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奶牛乳房炎是奶牛最常见的疾病之一.该病主要由细菌引起,在牛群中广泛存在,其中无乳链球菌(Streptococcus agalactiae)、停乳链球菌(Streptococcus dysgalactiae)和乳房链球菌(Streptococcus uberis)是奶牛乳房炎主要的致病性链球菌.试验采用THB(Todd-Hewitt Broth)固体选择性培养基和色素试验培养基快速分离无乳链球菌和乳房链球菌,并结合生物梅里埃开发的VITEK全自动细菌鉴定仪进行准确鉴定,从而建立一种从奶样中快速分离无乳链球菌和乳房链球菌的常规方法. 相似文献
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《动物营养学报》2021,33(9)
本试验旨在获得植物来源的脲酶抑制剂并探究其对瘤胃细菌脲酶抑制的基本特征。首先试验以奶牛瘤胃脲酶为靶标,利用分子对接虚拟筛选植物源化合物库,结合瘤胃细菌脲酶活性抑制试验,探究抑制效果最好的化合物对瘤胃细菌脲酶的半抑制浓度(IC50)值、酶动力学特征以及作用位点,最后通过瘤胃微生物体外厌氧培养试验评价该化合物对尿素分解的影响。结果表明:1)在同浓度条件下,瑞香素对瘤胃细菌脲酶的抑制效果最好。2)瑞香素对瘤胃细菌脲酶的IC50值为(93.43±3.87)μmol/L,是瘤胃细菌脲酶的混合型抑制剂。3)硫醇试剂存在时,瑞香素对瘤胃细菌脲酶的抑制效果显著降低(P0.05),分子对接结果显示瑞香素与氨基酸残基Ala-166、His-245、Lys-216、Ala-362、Cys-318形成相互作用。4)瑞香素能显著减缓瘤胃微生物体外厌氧培养2、4、6 h后体系中尿素的分解(P0.05)。综上所述,瑞香素能通过与瘤胃细菌脲酶活性中心的氨基酸相互作用来抑制脲酶的活性,减缓尿素的分解。 相似文献
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新型脲酶抑制剂对绵羊瘤胃酶活性和细菌总数的影响 总被引：10，自引：1，他引：9
为了研究新型脲酶抑制剂对绵羊瘤胃酶活性和细菌总数的影响 ,进行了两个实验。实验一 ,采用反转设计 ,用4头装有瘤胃瘘管的绵羊 ,分别测定了瘤胃液中脲酶、纤维素酶、蛋白水解酶、总脱氢酶的活性和瘤胃细菌总数。结果表明 ,在瘤胃内灌注50mg脲酶抑制剂 (氢醌 ,HQ )可以使脲酶的活性降低65 % (P<0.01) ,使纤维素酶的活性提高28 % (P<0.05) ,对蛋白水解酶、总脱氢酶的活性和瘤胃细菌总数没有影响(P>0.05)。实验二 ,采用滤纸片法观察了氢醌在10、20、40和80mg/L浓度范围内对瘤胃微生物的抑制作用。测定结果表明 ,除了80mg/L氢醌对瘤胃微生物有微弱的抑制作用外 ,其它浓度的氢醌对瘤胃微生物的生长没有影响。上述结果表明 ,HQ是瘤胃微生物脲酶的专一性抑制剂 ,对瘤胃微生物的繁殖和代谢活性无不良影响。HQ在较低浓度范围内使用 ,就可以非常有效地减缓瘤胃中尿素的释放速度 ,对瘤胃微生物和宿主动物安全 ,无毒副作用 ,在反刍动物尿素利用方面具有非常大的开发潜力。 相似文献
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在奶牛生产上应用的非蛋白质氮,主要包括尿素、缩二脲、异丁叉二脲和铵盐。奶牛是反刍动物,具有瘤胃、网胃、瓣胃和皱胃四个胃室。由于奶牛瘤胃中微生物的作用,使奶牛对蛋白质及含氮化合物的消化代谢具有特殊性。饲料蛋白质进入瘤胃后约有60%～70%的蛋白质首先被瘤胃微生物降解为氨基酸和氨。生成的这些氨基酸和氨一部分用于微生物合成菌体蛋白外,其余的氨由瘤胃壁吸收经门静脉随血液进入肝脏合成尿素。合成的尿素一部分经唾液和血液返回到瘤胃再利用,另一部分则从肾排出体外。瘤胃中80%的细菌可以以氨作为生长的唯一氮源合成菌体蛋白,这些… 相似文献
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采用PCR-DGGE技术分析比较了乳房炎和健康奶牛乳中微生物种群结构以及乳杆菌属(Lactobacillus)和纤毛虫属(Ciliates)菌群生物多样性差异,并对结果进行偏最小二乘法显著性分析(PLSDA)。结果表明,乳房炎患牛乳区细菌和纤毛虫菌群组成较健康奶牛复杂,而乳杆菌属菌群的DGGE图谱条带丰度、Shannon-Wiener指数却都显著低于健康奶牛;且乳房炎患牛乳区特异性菌种是无乳链球菌(Streptococcus agalactiae)、大肠杆菌(Escherichia coli)和不能培养的链球菌(Uncultured Streptococcus),而健康奶牛乳区特异性菌种是乳杆菌和双歧杆菌(Bifidobacterium),因此,可以推断出乳杆菌可能是抑制乳房炎病原菌感染的重要细菌类群。PLS-DA得分图也清晰地显示乳房炎患牛和健康奶牛乳区微生物区系结构存在显著差异。 相似文献
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尿素是一种高效有机化肥,广泛应用于农业生产。但它也能作为反刍家畜非蛋白氮来源饲养牛羊。尿索含氮量46％,一公斤尿素相当于2.8公斤蛋白质(1×0.46×6.25=2.8),或相当于7—8公斤植物油饼所含的氮,是很有潜力的蛋白质饲料来源。尿素是不能直接被家畜作为营养物质利用的。但牛是反刍动物,瘤胃内含有大量微生物和纤毛虫。瘤胃微生物能分泌一种活力极强的脲酶而分解尿素,(NH_2)2_CO H_2O→2NH_3 CO_2,微生物利用其分解出来的氨和瘤胃的有机酸作为营养物进行繁殖、生长和发育,並进一步合成菌体蛋白。菌体蛋白进入真胃后,被消化吸收,供畜体利用。 相似文献
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奶牛日粮中的非蛋白氮(NPN)使用指南 总被引：1，自引：0，他引：1
奶牛有能力将非蛋白氮(NPN)转化为蛋白质。在有适量的碳水化合物和矿物质的前提下,瘤胃微生物可利用NPN生产它们自身的菌体蛋白质,而这种菌体蛋白对奶牛是有利的,在家畜的饲料中,大多数使用尿素来充当NPN的来源,这仅仅是由于价格的因素,即用NPN原料生产的蛋白质,比使用油类籽实或动物原料生产蛋白质便宜。但是在使用NPN喂奶牛时,有两个主要的缺点: 相似文献
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与单胃动物不同,反刍家畜瘤胃中共生的微生物区系能将非蛋白的含氮化合物合成蛋白质。在反刍家畜日粮中加入尿素,由于瘤胃微生物和脲酶的作用,尿素被水解成氨。瘤胃微生物利用这些氨合成菌体蛋白质。 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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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
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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