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81.
鲁北滨海地区引种豆科牧草的灰色关联度分析 总被引:2,自引:0,他引:2
试验在鲁北滨海地区对经一般观察后初步入选的14种豆科牧草进行了观察,并采用灰色关联度分析法以干草产量、鲜草产量、繁殖系数、折干率、叶量率、生长速度为主要指标进行综合评价。结果表明:综合性状最好的豆科牧草是草木樨属牧草,其中白花草木樨尤为突出;其次为沙打旺和美国苜蓿,也是适于鲁北滨海地区种植的豆科牧草。 相似文献
82.
《Strength and Conditioning Journal》2020,73(2):321-328
Since Euro-American settlement of the region, biological diversity of the northern Great Plains has been adversely affected, mainly by agricultural conversion. The role of invasive plants in degradation of remaining prairies has gained attention in recent years but remains poorly understood. Floristic composition of US Fish and Wildlife Service (Service) prairies is significantly altered, mainly by invasion of smooth brome (Bromus inermis Leyss.), Kentucky bluegrass (Poa pratensis L.), and woody vegetation. We measured floristic composition of about 90 000 ha of Service-owned mixed-grass and tallgrass prairie in North Dakota, South Dakota, and northeastern Montana. Our primary objective was to identify factors associated with greater native grass-forb plant assemblages, while conversely identifying features more aligned with Kentucky bluegrass, smooth brome, and low shrub invasion. Service-owned prairies had a higher frequency of native grass-forb farther from habitat edges, such as cropland boundaries and roads, and on harsher ecological sites composed of poorer soils, steeper slopes, or with southern and western exposures. Kentucky bluegrass, smooth brome, and low shrubs differed in their respective responses to explanatory variables we considered and also reportedly differ in response to management actions such as fire and grazing. Therefore, prairie managers can expect significant challenges during restoration management in cases where two or more of these invaders occur. By understanding patterns of invasion related to edaphic, edge, and landscape features, prairie restorationists can focus on areas where the probability of restoration success is greater and better understand how these features might influence restoration success or failure. 相似文献
83.
84.
de Mello DM da Silva V Rosas F 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2011,40(1):74-77
Background: Establishment of reference values for serum biochemical analytes is important for monitoring health and physiological status of captive animals. Objective: The purpose of this study was to measure and report ranges for serum biochemical analytes in Amazonian manatees (Trichechus inunguis). Methods: Blood samples were collected from 24 healthy captive Amazonian manatees that comprised a mixture of adults, subadults, and calves and males and females; serum analytes were measured and analyzed using a dry reagent bench‐top chemical analyzer. Comparisons were made between sexes and with previously published values of closely related species. Results: Medians and ranges (minimum–maximum) of values for the analytes were: lactate dehydrogenase (LDH), 151 (111–278) U/L (n=20); creatine kinase, 144 (76–315) U/L (n=11); alanine aminotransferase, 10 (2–28) U/L (n=18); aspartate aminotransferase, 14 (5–28) U/L (n=21); γ‐glutamyltransferase, 47 (36–73) U/L (n=21); amylase, 1428 (1010–1874) U/L (n=21); alkaline phosphatase, 73 (36–141) U/L (n=19); total protein, 6.8 (6.2–8.0) g/dL (n=24); albumin, 3.3 (2.6–4.1) g/dL (n=21); cholesterol, 188 (101–399) mg/dL (n=21); triglycerides, 126 (60–236) mg/dL (n=21); glucose, 47 (22–69) mg/dL (n=21); urea, 43 (21–69) mg/dL (n=21); uric acid, 1.1 (0.5–1.8) mg/dL (n=22); creatinine, 2.2 (1.5–3.3) mg/dL (n=22); total bilirubin, 0.2 (0.2–2.0) mg/dL (n=21); calcium, 12.7 (10.2–18.6) mg/dL (n=24); iron, 282 (207–457) μg/dL (n=13); and magnesium, 6.9 (4.3–8.9) mg/dL (n=20). With the exception of LDH, no differences were observed between sexes. Conclusions: The ranges obtained in this study provide important preliminary estimates for concentrations and activities of serum analytes in Amazonian manatees until a larger reference interval study can be conducted. 相似文献
85.
Metlholo Andries Phukuntsi Helene Brettschneider Desiré L Dalton Teresa Kearney Jacqueline Badenhorst Antoinette Kotze 《African Zoology》2016,51(1):69-76
DNA barcoding has been proposed as a method for species identification. However, this method has been criticised for its over-reliance on a single mitochondrial gene. In this study, four mitochondrial gene regions and one nuclear gene region were used to investigate their different abilities to identify tissue associated with museum specimens of Aethomys chrysophilus, Aethomys ineptus and Micaelamys namaquensis. Aethomys chrysophilus and the more recently elevated A. ineptus are indistinguishable on morphological grounds; however, their ranges are largely parapatric with only one syntopic locality currently known. All of the mitochondrial gene regions were able to separate M. namaquensis from A. chrysophilus and A. ineptus, but they varied in their abilities to resolve differences between A. chrysophilus and A. ineptus. The sequence results identified a specimen from KwaZulu-Natal that was misclassified and should have been identified as A. ineptus. Seven specimens that had not been reclassified following the elevation of A. ineptus to species level were identified as A. ineptus. Individuals of A. chrysophilus from Malawi could not be classified as either A. chrysophilus or A. ineptus, and may be a hybrid or a new, distinct species. This study indicates that DNA barcoding may be used to separate M. namaquensis from A. chrysophilus and A. ineptus, and although it was not able to separate A. chrysophilus and A. ineptus, it did indicate specimens from Malawi may be a new cryptic species. 相似文献
86.
黑土滩混播人工草地种间竞争力的研究 总被引:1,自引:0,他引:1
文章在"黑土滩"退化草地上,通过对多种牧草的混播组合试验,研究了"黑土滩"混播人工草地种间竞争的动态关系。通过4年的试验观测表明:合理的混播组合及适当的草地管理,能有效地提高人工植被的牧草产量。并且随着生长年限的延长,各组合的相对产量总和(RYT)逐渐增大,种植当年种间竞争大于种内竞争(RYT〈1),环境资源仍有一定的利用空间;第2~4年种间竞争小于种内竞争(RYT〉1),各牧草的生态位发生了不同程度的分离。"垂穗披碱草+青海草地早熟禾+青海中华羊茅+青海冷地早熟禾"和"垂穗披碱草+青海草地早熟禾+青海中华羊茅+青海冷地早熟禾+碱茅"混播组合能获得相对稳定的群落。 相似文献
87.
为探明玉米‖花生茬口显著提高冬小麦旗叶的光合速率和产量的光反应机理,研究了玉米‖花生茬口(间作茬口,ICR)、玉米茬口(MCR)和花生茬口(PCR)及不同施磷水平对冬小麦播前土壤含水量、冬小麦花后旗叶的气体交换参数、光系统Ⅱ(PSⅡ)、光系统I(PSⅠ)及二者间的性能协调性的影响。结果表明,间作茬口较玉米茬口显著提高了冬小麦播前土壤含水量及旗叶的净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和PSⅡ反应中心供(Wk)/受体侧(Vj)的活性,增强了单位面积吸收的光能(ABS/CSo)、捕获的能量(TRo/CSo)和进入电子传递的光能(ETo/CSo)。间作茬口较玉米茬口显著提高了冬小麦扬花期旗叶PSⅡ初级光化学最大量子产额(φpo)、转化效率(Ψo)、电子传递效率(δRo)及乳熟期的PSⅠ的性能(ΔI/Io)、PSⅡ与PSⅠ协调性(ΦPSⅠ/PSⅡ)和籽粒产量,较花生茬口显著提高了乳熟期的φpo和δRo值。施磷提高了Pn、ABS/CSo、TRo/CSo、ETo/CSo、φpo、Ψo、δRo、ΔI/Io和ΦPSⅠ/PSⅡ值。这说明间作茬口较玉米茬口提高了冬小麦旗叶光反应中心活性,从而提高净光合速率,重要原因可能是间作茬口能保持耕层较高的土壤含水量。 相似文献
88.
本文旨在研究小麦型日粮中添加木聚糖酶和植酸酶对肉鸡生长性能、回肠氨基酸表观消化率及矿物元素沉积的影响。试验选择1日龄科宝白羽肉仔鸡850只,随机分成5组,每组5个重复,每个重复34只鸡。一共有5种日粮,即低磷日粮、高磷日粮、低磷日粮+2000 IU/kg木聚糖酶、低磷日粮+500 FTU/kg植酸酶,低磷日粮+2000 IU/kg木聚糖酶+500 FTU/kg植酸酶,试验进行21 d。低磷组较高磷组显著降低了肉鸡的日增重、日采食量及趾骨灰分含量(P <0.05),与低磷组相比,木聚糖酶组显著降低了肉鸡的料比(P <0.05),而植酸酶组显著提高了肉鸡日增重、日采食量、趾骨灰分及饲料利用率(P <0.05)。复合酶组显著提高了15种氨基酸回肠表观消化率(P <0.05)。与低磷组相比,木聚糖酶组显著提高了表观消化能和可消化代谢能及回肠氮消化率(P <0.05),而植酸酶显著提高了氮沉积及回肠氮消化率(P <0.05),复合酶组显著提高了代谢能、可消化代谢能及氮沉积量(P <0.05)。植酸酶和复合酶组较高磷组显著提高了磷表观消化率和沉积量(P <0.05),但低磷组较高磷组显著提高了钙的表观消化率(P <0.05),植酸酶酶和复合酶组较其他3组显著提高了钾的沉积量(P <0.05)。结论 :小麦型日粮同时添加植酸酶和木聚糖酶对肉鸡生长和消化的影响要优于单独添加这两种酶。 相似文献
89.
非洲猪瘟流行病学研究进展 总被引:1,自引:0,他引:1
非洲猪瘟(African swine fever,ASF)主要在非洲大陆流行,它通过偶然机会侵入到欧洲和美洲,之后进一步侵袭到了东欧和高加索地区,且到目前也未完全控制。非洲猪瘟病毒(African swine fever virus,ASFV)可通过软蜱传播,感染野猪和家猪,其在特定生态系统中的生存能力由它所在的野生宿主种群和畜牧生产系统来界定。ASF是可导致家猪和野猪死亡率极高的病毒性疾病,且因缺少有效的疫苗和治疗方法而造成巨大的经济损失。除了预防和扑杀,暂无其他更好的应对方法,所以需要很好地了解ASF流行病学,预防和控制其传播,以便实施更多有针对性的措施。 相似文献
90.