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随着饲用抗生素及化学药物广泛的禁用 ,需研究替代方法以确保畜牧业不会受到影响 ;对家禽的研究结果表明 ,被饲料中抗生素抑制的产气芽孢杆菌若大量繁殖将会引起胃肠疾病并导致畜产品产量和品质的下降。因此 ,研制促畜禽生长的抗生素替代品至关重要。1 抗生素的替代品一种抗生素替代品如纤维素酶可增加饲料消化率并促进肠道菌群的平衡。消化后的营养成分被鸡体吸收用于能量代谢和生长而不是被肠道微生物消耗。另一个替代品是甜菜碱 ,它能降低肠道寄生虫如艾美耳球虫引起的损伤 ,抑制球虫的再次感染 ,降低肠炎的发生率。细菌素是由某些细菌… 相似文献
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通过饲料中添加抗生素以及直接饲用微生物添加剂可改善动物的生产性能。虽然抗生素具有抗菌的作用,但某些抗生素和直接饲用微生物结合使用可对畜禽产生协同效应。——原编者按人们在畜禽饲粮中添加亚治疗浓度的抗生素来提高动物生产性能的做法已有近40年的历史了(Jukes,1990)。直接饲用微生物(酵母和细菌)越来越被饲料制造商所接受。部份原因是对这些微生物在肠道中的作用有了更好的了解(Fuller,1986)。据信,直接饲用微生物改善动物性能的原理是通过竞争性排斥致病菌,保持肠道促进养分消化和吸收的最佳条件,或是产生促进生长的物质。 相似文献
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随着当代畜牧业的发展,饲用微生物添加剂越来越多地在畜牧生产上推广应用,它通过调节动物体内微生物菌群的平衡而达到防病治病或促进动物生产的目的,并克服了抗生素在这些方面表现出的种种弊端,如残留、过敏、抗药性等,因此在畜牧生产上的应用越来越受到重视。1饲用微生物添加剂的概念饲用微生物添加剂就是在饲料中添加一种对畜禽有益的活菌制剂,论其功能不外乎两大类,一类是能提高动物对饲料的利用率,并能促进其生长,称之为微生物生长促进剂。另一类是参与肠道内微生物群平衡,能起到抑制致病性能,间接地起到促动物生长作用,称… 相似文献
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饲用抗生素的促生长作用机制及其替代技术研究 总被引:7,自引:0,他引:7
饲用抗生素是一种畜禽促生长剂,在畜牧生产上的应用已有50多年的历史。改革开放以来,我国一直重视饲用抗生素的研究,特别是近十年来,在国家“八五”和“九五”科技攻关项目支持下,我国在对饲用抗生素基础研究和产品生产方面都取得了显著成绩。在产品上,从原来全部依赖进口转变为今天的100%自主研制和生产,并有批量出口。在促生长机制等基础研究方面,研究提出了饲用抗生素的免疫屏障促生长作用机制,建立了饲用抗生素、免疫系统和肠道微生物三元平衡关系;揭示了饲用抗生素与免疫增强剂在促生长效果上的辩证关系,初步建立了多靶点筛选研究模型,为今后研究新的畜禽促生长剂以及饲用抗生素替代技术奠定了基础。饲用抗生素是一种药,目前关于对其合理使用和替代技术研究已引起科学界的广泛关注。另外,由于其关系到食品安全和人体健康,因此,饲用抗生素问题也已成为社会广泛关注的热点。欧盟已首先公布了禁止饲用抗生素的法令,世界其它国家政府也在研究对策。植物提取物和有益微生物是研究替代饲用抗生素的重要途径,目前在实验室内已获得成功。今后应加强对饲用抗生素安全性方面的研究,从系统科学出发,以提高畜产品质量为目的,研究开发行之有效的饲用抗生素的安全技术和替代技术,兴利除弊,促进畜牧经济发展。 相似文献
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芽孢杆菌对畜禽生产性能的影响 总被引:1,自引:0,他引:1
自从发现饲用抗生素可通过影响肠道微生物初期在宿主体内的定植,从而起到促生长的作用后,抗生素的应用在畜牧业方面产生了巨大的经济效益。调查表明,抗生素在畜牧业上的应用可使鸡肉年产量提高32%,蛋产量提高15%,猪肉产量提高4%,牛肉产量提高4%。但由于抗生素的大量使用,随之出现的负面效应也日益突出,表现为病原微生物产生耐药性和药物在动物产品中残留,从而对人类的健康产生潜在的危害。因此,抗生素替代品益生菌、酶制剂和酸制剂等的研究与开发成为近年来绿色饲料添加剂的热点,其中益生菌备受关注。 相似文献
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饲用抗生素替代品研究进展 总被引:1,自引:0,他引:1
自抗生素被发现和使用以来,其作用功不可没,抗生素可通过抑制环境中的抗生长因子产生的亚临床症状而促进动物生长,部分抗生素可以使蛋白质代谢相应得到改善,降低血液中氨、尿酸含量,增加氮沉积。抗生素还具有降低肠壁厚度、改善肠黏膜结构、降低肠道维持需要的作用,促进营养物质的吸收,从而提高生产性能和养殖效益。但随着抗生素的使用,抗生素的负面影响日渐突出,细菌抗药性越来越普遍,越来越严重,长期使用抗生素造成畜禽机体的免疫力下降,可引起畜禽内源性感染和二重感染,会在畜产品和环境中造成残留。另外,抗生素还有致基因突变、引发畸形和诱发癌症等毒副作用。因此,寻求抗生素替代品已成为近年来研究的焦点,研发安全、高效、绿色的新型饲用抗生素替代产品已迫在眉睫。虽然一些抗生素替代品在不同程度上可以替代抗生素,并对动物的生长和健康产生了积极的影响,然而一些饲用抗生素替代产品在抗病促生长效果和全面替代抗生素方面还存在较大局限性,本期特邀国家粮食局科学研究院李爱科研究员就饲用抗生素替代品研究的进展和存在的一些问题进行阐述,希望能对行业从业者有所启发。 相似文献
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世界上许多国家都准许在饲料中采用亚治疗量的抗生素作为生长促进剂。然而 ,这种做法正在受到越来越严厉的责问 ,因为这种做法有可能将抗药性传递给人类的病原菌。欧盟各国当前禁用了大多数这类抗生素 ,并且看来会在不久的将来完全禁用非处方饲用抗生素。所以人们一直在搜寻有效的饲用抗生素替代物。促生长抗生素和生菌剂各自都能以其独特的方式改变肠道微生物群体的组成并且减少病原菌的数量 (Lindsey ,1992 )。抗生素生长促进剂能减少肠道菌总数 ,包括格兰氏阴性病原菌。生菌剂则向机体提供芽孢杆菌、乳杆菌、链球菌、拟杆菌、酵母和霉菌… 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