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钒与动物营养 总被引：3，自引：0，他引：3
20世纪 60年代以前 ,人们认为钒是一种有毒的元素 ,直到 1 975年Ｃｈｅｒｎｅｙ从马骨骼肌中分离出了Ｎａ -Ｋ -ＡＴＰ酶的抑制物 ,证实该抑制物为钒酸盐 ,人们才开始重视对钒生理、生化作用的研究 ,并认识到钒是人和动物的必需微量元素。进入 2 0世纪 80年代 ,钒的化合物开始被应用于糖尿病、贫血、结核、神经衰弱等疾病的治疗 ,随着科学研究水平提高 ,人们对钒的认识也越来越深入。1 分布元素周期表中钒属于第四周期ＶＢ 族 ,原子量 50 941 ,熔点 1 9 9℃ ,沸点 340 0℃。自然界中有两个钒的同位素51Ｖ和50 Ｖ ,而4 6Ｖ、4 7Ｖ、4 8Ｖ、… 相似文献
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猪水肿病是某些血清型的溶血性大肠杆菌引起的肠道毒血症,故又称为肠毒血症.此病最早是1938年由爱尔兰Shanks发现[1],Bertschinger等报道几乎全世界都有发生[2],我国20世纪50年代后期发现本病,20世纪60年代全国各地均有报道[3].锦州地区近几年发病有上升趋势,发病率为1.70%～8.43%,死亡率为1.02%～6.75%.本文为鉴定锦州地区流行的主要血清型及其生物学特性,同时进行药物敏感性试验,为防治猪水肿病提供理论依据. 相似文献
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人类利用蜂产品的历史悠久,蜂蜜、蜂蜡作为传统的蜂产品已有数千年,蜂巢、蜂蛹虫、蜂花粉等蜂产品的利用历史也很久远,蜂王浆作为现代蜜蜂产品的主要品种,其发展利用历史已有记载。在国外,1792年弗郎克斯·哈伯(FrancoisHuber)提出王浆一词[1];1852年美国朗斯特罗什先生收集了足够数量的蜂王浆请化学家对蜂王浆的成分进行分析研究[2];1888年德国化学家A·Von·pIanta对蜂王浆的成分进行了研究分析;20世纪20年代加拿大一养蜂者随意将蜂群中多余王台削下来被母鸡吃掉,第二天母鸡产下一个较大鸡蛋[4],这一发现引起科学家的注意。从此,蜂王浆… 相似文献
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江苏省如东县自20世纪80年代中期开始致力于猪人工授精技术推广工作,经过30多年努力,如东县母猪栏存已达25万头左右,猪人工授精普及率已达98%以上[1],一跃成为江苏省母猪饲养第一大县、全省猪人工授精技术推广示范县,其生猪与苗猪产业被列为江苏省农业优势特色产业[2]。本文叙述了如东县开展猪人工授精技术推广的工作措施和取得的成效,总结了当前猪人工授精技术推广过程中存在的欠缺和不足,对今后如何做好猪人工授精技术推广工作提出了指导性意见。 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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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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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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乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制. 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