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草地生态系统不但为人类提供食物、饲料、药物等重要资源,而且还为人类提供许多工业技术难以替代的公益,包括空气和水体的净化、缓解洪涝和干旱、土壤的产生及其肥力的维持、生物多样性的产生和维持、气候的调节等.草地生态系统是中国西部分布最广的自然生态系统,草地生态系统经营也是当地经济发展的重要支柱之一.但不合理的工农业生产活动已经严重破坏了草地生态系统的可持续能力.如果继续当前的不合理生产方式,以草地为发展基础的畜牧业经济将受到极大限制,西部经济繁荣也将失去其重要优势,同时严重威胁到西部甚至全国生态环境稳定和居民生活安全.采取合理高效的发展策略,保护和科学利用草地生态系统迫在眉睫. 相似文献
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草地生态系统是最大的陆地生态系统,包括草地植物生态系统、动物生态系统和人类社会系统等子系统。如果各子系统间耦合性高,系统则表现为结构合理、系统稳定和子系统间物质流、信息流和能流等功能的作用效率高。青海省草地资源丰富,近年来由于不合理管理下,子系统之间相悖性表现得尤为突出,阻碍了当地草业和畜牧业的发展。利用系统耦合理论,建立系统间的和谐关系,实现草地畜牧业高效、稳定地发展。 相似文献
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草地生态系统是最大的陆地生态系统,包括草地植物生态系统、动物生态系统和人类社会系统等子系统。如果各子系统间耦合性高,系统则表现为结构合理、系统稳定和子系统间物质流、信息流和能流等功能的作用效率高。青海省草地资源丰富,近年来由于不合理管理下,子系统之间相悖性表现得尤为突出,阻碍了当地草业和畜牧业的发展。利用系统耦合理论,建立系统间的和谐关系,实现草地畜牧业高效、稳定地发展。 相似文献
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草地生态系统公益保护与西部开发 总被引:9,自引:2,他引:9
草地生态系统不但为人类提供食物、饲料、药物等重要资源,而且还为人类提供许多工业手工艺技术难以替代的公益,包括空气和水体的净化、缓解洪涝和干旱、土壤的产生及其肥力的维持、生物多样的产生和维持、气候的调节等。草地生态系统是中国西部分最广的自然生态系统,草地生态系统经营也是当地经济发展的重要支柱之一。但不合理的工业生产活动已经严重破坏了草地生态系统的可持续能力。如果继续当前的不合理生产方式,以草地为发展基础的畜牧业经济将受到极大限制,西部经济繁荣也将失去其重要优势,同时严重威胁到西部甚至全国生态环境稳定和居民生活安全。采取合理高效的发展策略,保护和科学利用草地生态系统迫在眉睫。 相似文献
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放牧牦牛是青藏高原的当家畜种,是草地畜牧业"草—畜—粪—土—草"物质养分循环系统的重要参与者。牦牛粪便还用可能是影响青藏高原高寒草地生态系统的重要方式之一。深入研究放牧牦牛粪便排泄行为及对草地生态系统的影响,对于科学利用放牧牦牛粪便,推动高寒草地畜牧业健康发展具有重要意义。 相似文献
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砒砂岩分布区地处毛乌素沙漠南缘,总土地面积11682 km2,其中草地7980.5 km2,占总土地面积的68.3%,畜禽品种较多,传统上是以养殖业为主的地区,具有发展畜牧业的资源优势.本地区还是我国正在开发的重要的煤炭基地.本文着重就该区畜牧业生态系统的草畜资源进行了调查与评价,并结合自然条件和畜牧业现状初步提出了该区畜牧业生态建设的途径和措施. 相似文献
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阐述了建立草地生态系统,对促进湟源县畜牧业可持续发展的重要性和必要性.在地处高寒,农业基础薄弱、自然灾害频繁、生态脆弱的地区,充分利用现有草地资源,加强退耕还林还草工程,实施封山育草、人工种草等,制定农林牧三结合发展计划,进一步促进湟源县畜牧业持续发展. 相似文献
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巴音布鲁克草原是巴音布鲁克区生态系统的主体,是该区畜牧业发展的重要物质基础和农牧民赖以生存的基本生产资料,是我州最大的绿色生态屏障,同时也是南疆重要的生态防线。近些年来,由于受全球气候变暖现象的影响,加上过度开发,超载过牧,巴音布鲁克草原90%以上的草地已经出现了不同程度的鼠害、沙化,重度退化的已达40%。生态危机已经成为该区实现脱贫致富奔小康的重大障碍。 相似文献
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草地生态系统服务功能及其价值评估研究进展 总被引:2,自引:0,他引:2
草地生态系统是维持自然生态系统格局、保护生态安全屏障、开展畜牧业生产和传承草原文化的基础。随着人类对草地生态系统服务功能不可替代性的深入认识,通过定量评估生态系统服务功能及其价值,对认识草地生态服务功能的重要性和生态资产增值具有重要的作用。在总结国内外生态系统服务功能及其价值文献基础上,对草地生态系统服务功能及其价值的内涵、生态服务价值评估方法及其特点和国内外研究现状进行了系统总结,分析了草地生态系统服务功能及其价值评估中存在的主要问题,提出了未来研究的发展方向。 相似文献
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草地是一种可持续利用的自然资源,它不仅是发展畜牧业生产的物质基础,而且是人类重要的生态屏障。但是草地也是一个脆弱的生态系统,如果不进行合理利用,将会导致草地生态系统的破坏。因此,要对天然草地进行管理和保护,合理利用, 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