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常见芳香族和脂环族化合物在反刍家畜瘤胃内的代谢 总被引:3,自引:0,他引:3
芳香族化合物在反刍动物瘤胃的厌氧微生物作用下,通过水解、还原等反应,发生生物转化和矿化。不同的芳香族和脂环族化合物具有各自的代谢特点与途径:羟基桂皮酸经微生物氢化形成的羟基-3-苯丙酸,再经O-脱甲基作用和脱羟基作用转变为3-苯基丙酸;羟基苯甲酸经脱羧和脱甲氧基作用转化为简单酚类;消化道内的微生物对环己烷羧酸转化为苯甲酸的芳香化过程不起作用,仅对奎尼酸和莽草酸转化为环已烷羧酸的过程起作用;氨基酸通过瘤胃微生物降解的可能途径主要是Stickland反应,即氨基酸通过氧化还原机理脱氨;香豆素可能不是哺乳动物体内苯甲酸的前体物质,瘤胃微生物对类黄酮降解的方式与大肠微生物不同;不同类型的单宁降解不同:水解单宁的尿代谢物一般与五倍子酸的分解产物一样,如果缩合单宁单体间稳定耦合链被断裂,那么其代谢途径可能与简单类黄酮的代谢过程类似;木质素单体很容易被生物转化,但木质素低聚体能经受一定程度的解聚作用。 相似文献
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长期封育对内蒙古羊草草地土壤有机碳组分的影响 总被引:3,自引:0,他引:3
封育是当前恢复和改良内蒙古草地的重要措施,也是实现草地固碳效应最有效的途径之一。本文利用内蒙古封育32年和自由放牧的羊草草地,分析了其土壤有机碳组分、土壤团聚体和土壤腐殖质组分碳含量的变化,并运用13C核磁共振波普法对土壤腐殖质的有机碳组分进行波普分析,探讨了长期封育对羊草草地土壤有机碳组分和土壤有机质结构的影响,期望能为科学地评估长期封育状况下草地固碳效应及其稳定性提供理论依据。实验结果表明:长期封育显著提高了草地土壤有机碳含量;在土壤有机碳组分中,除土壤微生物碳(MBC)含量降低外,其碳组分含量都相应增加。其中,易氧化有机碳(EOC)含量增加最为明显,长期封育草地是自由放牧草地土壤的4.53倍;长期封育显著提高了草地土壤0.25~2 mm团聚体所占比例及其有机碳含量;长期封育提高了草地土壤腐殖质中的胡敏酸碳(HAC)、胡敏素碳(HUC)含量和胡敏酸/腐殖质碳,降低了富里酸碳(FAC)的含量,封育草地土壤的HAC/FAC是自由放牧草地土壤的5.66倍。此外,长期封育草地土壤的脂族碳含量显著增加,芳香度相应增加,疏水碳/亲水碳增大。总之,长期封育不仅提高了草地土壤有机碳贮量,还能改善草地土壤结构、增强土壤有机碳的稳定性。 相似文献
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本试验以短花针茅(Stipa breviflora)荒漠草原淡栗钙土为研究对象,分析地形、放牧强度对土壤胡敏酸、富里酸和胡富比的影响,并探讨了土壤胡敏酸、富里酸与土壤有机碳的关系。结果表明,淡栗钙土胡敏酸和富里酸含量均较低,随着海拔上升,土壤胡敏酸和富里酸均有降低趋势,随放牧强度的增大土壤胡敏酸和富里酸均显著降低(P<0.05)。随海拔上升,其胡富比值降低,放牧强度影响胡富比值,其中重度放牧对胡富比值影响显著(P<0.05)。随着海拔上升,腐殖酸的各组分与有机质间的相关性增加,随放牧强度的增大其腐殖酸的各组分与有机质间的相关性降低。研究区适合轻度放牧,而且围栏放牧时,根据地形部位的不同,载畜率也应不同。 相似文献
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不同草甸植被类型下土壤腐殖质及有机磷类型探讨 总被引:18,自引:3,他引:15
采用熊田法和Bowman-Cole法研究了不同草甸植被类型下的土壤中的腐殖质类型及土壤中的有机磷组分,结果表明,各类土壤总有机质含量变化在7.00%-12.28%之间,游离胡敏酸(fHA)的比率为51.67%-60.10%游离富啡酸(fFA)的比率为80.01%-86.46%;在可提取腐殖质中胡酶酸所占比率为47.99%-56.98%。此外,土壤中腐殖质的相对色度(RF)和E4也都有明显的差异。在土壤的有机磷组分方面,活性有机磷的含量比较低,变化在2.35%-6.01%之间;中等活性有机磷的含量在高海拔寒冷地区较低,变化在32.58%-34.66%之间,在低海拔谷地地区较高,变化在41.97%-52.18%之间;低温有利于中等活性有机磷向中等稳定性有机磷转化;而各类高度稳定性有机磷含量较低,仅高于活性有机磷,均在15%左右。有机碳/有机磷(Co/Po)比值均大于100,有机质中的相对含磷量较低。藏嵩草+华偏穗草草甸土壤中全磷含量高,其中又以无机磷为主,是该植被类型下土壤的主要特性。 相似文献
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高寒草甸土壤腐殖质组成及性质的研究 总被引:1,自引:0,他引:1
不同草甸植被下土壤有机质含量不同,同时腐殖质特性亦有较大差异。采用熊田法研究表明,不同类型的草甸土壤总腐殖质含量高低变化较大,总有机质含量变化在7.00%~12.28%之间,游离胡敏酸比率为51.67%~60.10%,游离富里酸比率为80.01%~86.46%;可提取腐殖质中胡敏酸所占经率为47.99%~56.98%。此外腐殖质相对色度、E4、也不明显差异。 相似文献
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本试验选择黄河源区果洛州玛沁县大武滩不同退化高寒沼泽湿地为研究对象,分层采集冻融丘和丘间土壤样品,分析退化过程中土壤腐殖质变化以及相关的环境因子。结果表明:冻融丘和丘间土壤腐殖质随着退化程度的加剧而下降,冻融丘腐殖质碳、胡敏素和胡敏酸未退化与轻度退化、重度退化差异显著(P<0.05),对退化较丘间敏感;冻融丘和丘间的腐殖质碳、胡敏酸、富里酸和胡敏素含量与土壤含水量、总氮呈显著正相关(P<0.05),冻融丘土壤腐殖质组分与容重呈显著负相关(P<0.01);冻融丘中纤维二糖水解酶(CBH)、β-1,4-木糖苷酶(BXYL)、α-1,4-葡萄糖苷酶(αG)、β-1,4-葡萄糖苷酶(BG)、亮氨酸肽酶(LAP)、β-1,4-N-乙酰基氨基葡萄糖苷酶(NAG)和脲酶(UR)对胡敏素形成具有显著的促进作用,丘间酶活性对土壤腐殖质的形成具有显著的促进作用。综上所述,高寒沼泽湿地退化导致土壤腐殖质减少,致使碳功能的下降,土壤水分、全氮和土壤酶有利于湿地土壤腐殖质的形成,建议在高寒沼泽湿地修复中加强土壤水分和有机肥的补充。 相似文献
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对12只安装有永久瘤胃及十二指肠瘘管的周岁细毛羯羊饲以不同代谢能水平和尿素添加量日粮的一系列试验得出绵羊瘤胃中每日生成微生物氮的数量在2.09~8.33 g之间;当日粮中瘤胃降解氮供给充足条件下,微生物产量与代谢能进食量密切相关;而瘤胃中可降解氮转化为微生物氮的效率在32.94%~82.64%之间,它和日粮中每兆焦代谢能所对应的瘤胃降解氮克数呈负相关;日粮中添加的尿素氮转化为微生物氮的效率范围为-1.03%~88.80%,它们既与日粮中总降解氮和总代谢能的比值相关,又与尿素氮占总降解氮的比例相关. 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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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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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