添加烟酸条件下绵羊瘤胃发酵底物降解动力学变化特征

试验用瘤胃液来自3只安装永久性瘤胃瘘管的绵羊,饲喂玉米-豆粕型基础日粮.通过体外试验,添加450 mg/kg烟酸,测定在不同培养时间内培养液中NH3-N浓度、瘤胃细菌N产量、原虫数量、总VFA量及乙酸、丙酸、丁酸产量和乙酸/丙酸值的降解动力学特征.结果表明:添加烟酸可提高培养液NH3-N利用率;培养液中细菌N、原虫数、总VFA量及乙酸、丙酸、丁酸产量随采样时间变化而呈不同的动力学变化趋势;但乙酸/丙酸值则不受采样时间变化的影响,与对照组相比差异不显著(P>0.05).     

星星草地上部6种元素含量季节动态及其分布

研究星星草人工草地地上部N、P、K、Na、Ca、Mg含量的季节动态及其在不同器官和不同株高的分布情况。结果表明,在生育期间,元素含量由大到小的顺序均为K>N>P>Na>Ca>Mg。其中K、N、P、Na和Mg随着生育期的进程含量递减,而Ca在生育后期变化较小。供试元素积累量及积累速率的季节动态与生物量的变化趋势较为一致,即先升后降。在开花期后元素和干物质开始向根部运输。N在穗中最多,P、Ca、Mg在叶中最多,而K和Na则主要分布在茎中。近地面和茎的最上部元素含量相对较少。开花期为星星草最适合的收获期。     

自贡黑山羊生后期生长发育规律的研究

对自贡黑山羊生后期的生长发育规律进行了研究,得出自贡黑山羊公羊8月龄前、母羊6月龄前的体尺、体重变化极显著,说明自贡黑山羊早期生长发育快、成熟早,具有典型的肉用山羊品种特征。     

财务信息对上市公司高层变动的影响分析

上市公司高层变动受多种因素的影响,经营业绩是其中一个重要因素,能有效反映公司经营绩效的财务信息,对高层变动的影响也是不容忽视的.通过对深市样本公司的高层变动与会计信息的实证分析,进一步证明了不同会计信息对高层变动的影响程度及二者的关系,从而为投资者和管理者及其他财务数据使用者提供有效的参考依据.     

Impact of climate change on the small mammal community of the Yukon boreal forest

Long‐term monitoring is critical to determine the stability and sustainability of wildlife populations, and if change has occurred, why. We have followed population density changes in the small mammal community in the boreal forest of the southern Yukon for 46 years with density estimates by live trapping on 3–5 unmanipulated grids in spring and autumn. This community consists of 10 species and was responsible for 9% of the energy flow in the herbivore component of this ecosystem from 1986 to 1996, but this increased to 38% from 2003 to 2014. Small mammals, although small in size, are large in the transfer of energy from plants to predators and decomposers. Four species form the bulk of the biomass. There was a shift in the dominant species from the 1970s to the 2000s, with Myodes rutilus increasing in relative abundance by 22% and Peromyscus maniculatus decreasing by 22%. From 2007 to 2018, Myodes comprised 63% of the catch, Peromyscus 20%, and Microtus species 17%. Possible causes of these changes involve climate change, which is increasing primary production in this boreal forest, and an associated increase in the abundance of 3 rodent predators, marten (Martes americana), ermine (Mustela ermine) and coyotes (Canis latrans). Following and understanding these and potential future changes will require long‐term monitoring studies on a large scale to measure metapopulation dynamics. The small mammal community in northern Canada is being affected by climate change and cannot remain stable. Changes will be critically dependent on food–web interactions that are species‐specific.     

Unmanned Aerial Vehicle − Based Rangeland Monitoring: Examining a Century of Vegetation Changes

Rangelands comprise a large component of the terrestrial land surface and provide critical ecosystem services, but they are degrading rapidly. Long-term rangeland monitoring with detailed, nonsubjective, quantitative observations can be expensive and difficult to maintain over time. Unmanned aerial vehicles (UAVs) provide an alternative means to gather unbiased and consistent datasets with similar details to field-based monitoring data. Comparing summer 2017 UAV images with long-term plot measurements, we demonstrate that rangeland vegetation cover changes can be accurately quantified and estimate an increase in total absolute shrub/subshrub cover from 34% in 1935 to > 80% in 2017 in central Arizona. We recommend UAV image-based rangeland monitoring for land managers interested in a few specific and dominant species, such as the foundation species, indicator species, or invasive species that require targeted monitoring. Land managers can identify and continuously monitor trends in rangeland condition, health, and degradation related to specific land use policies and management strategies.     

青海省海晏县放牧牦牛体重及血清生化指标的全年监测

本试验旨在探明青海省主要牦牛饲养区海晏县牦牛的营养状况,为制定添补措施提供科学依据。于2015-09—2016-08跟踪测定了青海省海晏县牧户草场天然牧草产量以及牦牛干物质采食量、体重和血清生化指标,同时分析平均日增重与血清生化指标的相关性。结果表明:天然牧草可食草产量7月份高于其他月份;春季牦牛干物质采食量显著高于秋、冬季(P0.05),秋季显著低于其他季节(P0.05);1月份、2月份、3月份、10月份、11月份、12月份牦牛平均日增重呈现负增长,4月份后逐渐上升,6月份、7月份显著高于其他月份(P0.05);血清葡萄糖(GLU)的含量7月份显著高于除6月份、10月份外的其他月份(P0.05);2月份、3月份血清尿素氮(UN)含量及碱性磷酸酶(ALP)活性低于其他月份;由相关性分析可知,平均日增重与血清UN含量呈显著的正相关(P0.05)。综合得出,青海省海晏县10月份至次年3月份为饲草供给不足,牦牛平均日增重呈现负增长,4月份后平均日增重逐渐上升,因此,建议轮牧的放牧形式下,10月份至次年3月份,采用天然草场配合补饲饲料的饲养方式。     

蛋鸡锰缺乏症的病理学研究

１日龄父母代罗曼（Ｌｏｈｍａｎｎ）蛋鸡１２０只,随机分为３组,分别喂以低锰（基础日粮含锰１３．６２ｍｇ／ｋｇ）、低锰高磷（基础日粮＋０．５％的磷）、补锰对照（基础日粮＋锰８０ｍｇ／ｋｇ）日粮。试验期８周。饲喂５～８周发病。低锰组发病率２６％,低锰高磷组２８％,补锰对照组无一发病。第４周时,体重分别为（２６７．９±８．３２）、（２１４．２±１０．４２）、（２６５．０±１２．１８）ｇ,低锰组、补锰对照组与低锰高磷组之间差异极显著（Ｐ＜０．０１）。肝锰含量分别为（５．４０±０．７４）、（２．８２±０．３６）、（８．４８±０．９６）ｍｇ／ｋｇ,补锰对照组与低锰组差异显著（Ｐ＜０．０５）,与低锰高磷组差异极显著（Ｐ＜０．０１）。发病症状：精神沉郁,不愿走动,伏卧,跛行,单腿发病病腿向外侧伸展,双腿发病则内收呈“Ｏ”字形或外展呈“八”字形。剖检跗关节肿大,胫骨髁骨骨质增生、肿大,髁间沟变平坦。组织学检查,胫骨骺生长板增殖区变窄,软骨基质中粘多糖减少。超微结构变化,心肌纤维、肝细胞、胫骨骺生长板软骨细胞、睾丸精原细胞等线粒体肿胀与空泡化。     

不同种类牧草对山羊瘤胃挥发性脂肪酸变化规律的研究

研究山羊瘤胃内放入装有不同种类牧草的尼龙袋后,瘤胃挥发性脂肪酸浓度的动态变化规律。选用带有瘤胃瘘管的山羊为实验动物,结合尼龙袋法测定3类牧草在山羊瘤胃中的挥发性脂肪酸浓度。结果表明,添加装有不同牧草的尼龙袋后,山羊瘤胃乙酸、丙酸、丁酸、总挥发性脂肪酸（TVFA）浓度及乙酸／丙酸值均呈先上升后下降的规律,并在4h达到峰值,其中乙酸浓度约为70．49％、丙酸浓度约为15．38％,瘤胃的发酵类型总体上偏向于乙酸-丙酸型．3类牧草均适用于山羊的科学饲养。由此可见,添加装有不同种类牧草的尼龙袋均会对山羊瘤胃挥发性脂肪酸产生影响,其原因主要与原料的蛋白质含量有关。     

内蒙古多伦县景观格局动态变化分析

根据内蒙古多伦县2000年TM影像和2008年SPOT5影像及地面调查资料,在ArcGIS和ERDAS等软件支持下,获得多伦县2期景观类型数据,并运用景观生态学原理与方法,分析了多伦县2000-2008年景观格局动态变化,以期为多伦县土地资源的合理规划与利用提供决策依据,也为荒漠化治理提供理论依据。结果表明:林地面积增长最快,增长了12.09倍,年变化率为1.51%,优势度指数增加明显,破碎度指数和分维数减小;沙地面积减小最为明显,减小了16107 hm²,占2000年沙地总面积的85.1%,年变化率为0.11%,随着斑块数量的增加破碎度指数呈增加趋势,沙地景观类型重心向西北方向转移21.13 km。草地斑块数呈减少趋势,但是斑块面积增加了36150 hm²,占2000年草地总面积的16.4%。综上所述,表明多伦县生态环境趋于良性发展。