共查询到20条相似文献，搜索用时 171 毫秒
1.
2.
3.
放牧和封育对青藏高原南缘亚高山草甸群落结构及物种多样性的影响 总被引：1，自引：0，他引：1
为探讨青藏高原南缘亚高山草甸的适宜管理措施,本研究以自由放牧、4年全年封育、4年生长季封育+非生长季放牧和20年生长季封育+季末割草管理下的亚高山草甸典型样地为研究对象,开展放牧和封育管理措施下亚高山草甸群落结构及物种多样性的比较研究。结果表明:退化亚高山草甸经4年的生长季封育+非生长季放牧管理,草地有害植物的优势地位降低,优良牧草的优势地位增加,物种丰富度显著下降,草地生产力、密度、盖度、多样性和均匀度无显著变化;经4年的全年封育管理,草地生产力、密度、盖度及优良牧草的优势度显著增加,优良牧草草地早熟禾(Poa pratensis)成为群落的单优势物种,群落的生态优势度急剧增加,丰富度、多样性和均匀度显著降低;经20年的生长季封育+季末割草管理,草地生产力、密度、盖度及优良牧草的优势度显著增加,草地早熟禾和大花嵩草(Kobresia macrantha)成为群落的优势物种,群落的生态优势度指数和丰富度指数显著增加,多样性和均匀度显著降低。可见,与自由放牧相比,3种封育措施均可增加滇西北退化亚高山草甸优良牧草的优势度,促进退化亚高山草甸植被的恢复,但封育后因群落中单个或少数物种在群落中的优势地位大大增加,草地中伴生种消失,物种丰富度和多样性降低。 相似文献
4.
Chitosan and its oligosaccharide derivatives (chito‐oligosaccharides) as feed supplements in poultry and swine nutrition 
下载免费PDF全文
下载免费PDF全文 S. Swiatkiewicz M. Swiatkiewicz A. Arczewska‐Wlosek D. Jozefiak 《Journal of animal physiology and animal nutrition》2015,99(1):1-12
Chitosan is a non‐toxic polyglucosamine, widespread in nature, which is deacetylated to varying degrees form of chitin, a component of exoskeleton of shrimps, crabs and insects. Because chitosan contains reactive functional groups, that is, amino acids and hydroxyl groups, it is characterised by antimicrobial, anti‐inflammatory, anti‐oxidative, antitumor, immunostimulatory and hypocholesterolemic properties when fed as dietary additive for farm animals. This article reviews and discusses the results of studies on the effects of dietary chitosan and its oligosaccharide derivatives on performance and metabolic response in poultry and pigs, that is, haematological, biochemical and immunological blood characteristics, microbiological profile of intestines, intestinal morphology and digestibility of nutrients, as well as on the quality of meat and eggs. The results of most of the experiments presented in this review indicate that chitosan used as a feed additive for poultry and pigs has some beneficial, biological effects, including immunomodulatory, anti‐oxidative, antimicrobial and hypocholesterolemic properties. These properties of chitosan, unlike many other kinds of feed additives, were often reflected in improved growth performance (body weight gain and/or feed conversion ratio) of young animals, that is, broiler chickens and weaned pigs. 相似文献
5.
Fetal loss in the dog and cat 总被引：1，自引：0，他引：1
S D Johnston S Raksil 《Veterinary Clinics of North America: Small Animal Practice》1987,17(3):535-554
Occurrence and type (resorption, abortion, stillbirth, mummification) of pregnancy loss in the dog and cat depend on the cause of the loss and the stage of gestation at which it occurs. General categories of known causes of embryonic or fetal death in the dog and cat include chromosome and developmental abnormalities of the fetus, infectious agents, maternal endocrine abnormalities, trauma, exogenous drugs, uterine torsion, and dystocia. Diagnosis of fetal loss and of cause of fetal loss relies on the history, physical examination, abdominal radiography and ultrasonography, serology, hormone assay, and on culture, pathology, and karyotype of fetal/placental tissue. Aggressive diagnostics at the time of fetal loss are essential to preventive strategies at subsequent pregnancies. 相似文献
6.
随着奶牛行业的快速发展,全株玉米青贮因其价格低、储存时间长、营养丰富、适口性好、饲料转换率高等优点,越来越受到奶牛养殖者的认可和青睐。但在青贮制作过程中,因养殖者青贮制作技术欠缺、经验不足、认知度低等原因,最终导致青贮制作失败。为提高全株玉米青贮制作水平,本文将从把控水分、隔绝空气、微生物处理、收贮管理等全株玉米青贮制作四项基本原则进行论述和分析,养殖者可通过把控最佳收割时间,严管留茬高度、切割长度、籽粒破碎程度,做到上料快、压窖快和封窖快,正确使用青贮发酵剂,做好封窖后维护管理工作,从而做出优质的青贮饲料,进一步提高奶牛产奶量和牧场经济效益。 相似文献
7.
枯草层是指由草坪草周期性脱落的根系、水平茎(匍匐茎和根状茎)和成熟的叶鞘叶片堆积起来而形成的,处于地表与绿色植物之间的半分解半腐烂状态的有机物。枯草层广泛存在于草坪生态系统中,其厚度会直接影响草坪质量、使用年限以及弹性、缓冲和耐践踏能力等运动质量,采取适当的措施减少枯草层的积累或加快枯草层的降解十分必要。本文结合国内外相关文献,对草种选择、修剪、打孔取心、垂直刈割、紫外线辐射、氮肥、石灰、杀虫剂、杀菌剂、生长延缓剂、蚯蚓、微生物、酶、生物材料等与枯草层的关系进行了归纳综述,并从改良土壤物化性质,改变土壤所含营养物质含量与比例,提高土壤中动物、微生物和酶的数量和活性3个方面阐述了这些措施影响枯草层降解的机理。 相似文献
8.
皮埃蒙特、利木赞牛三元杂交组合幼牛产肉性能研究 总被引：3，自引：0，他引：3
本文对皮埃蒙特公牛×西黄杂种母牛 (西门塔尔公牛×当地黄牛 ,下简称皮西黄 )、利木赞公牛×西黄杂种母牛 (下简称利西黄 )两组合的三元杂交种幼牛肉用性能进行了研究。结果表明 ,两个组合肉性良好。 9月龄体重分别达 2 88.4kg和 2 5 9kg;育肥期平均日增重达 879.4g和 846.1 g。皮西黄屠宰率、净肉率、胴体产肉率和熟肉率分别为 5 8.2 5 %、47.5 0 %、81 .94%和 65 .4% ,利西黄分别为 5 5 .33%、45 .67%、82 .0 9%和 67%。皮西黄肉骨比、肉脂比、胴体优质切块比例和眼肌面积分别为4.5 5、1 0 .86、35 .1 2 %和 73.70 cm2 ;利西黄分别为 4.61、1 0 .2 3、33.38%和 63.1 0 cm2 。皮西黄产肉性能强于利西黄。 相似文献
9.
流行病学模型可作为动物疫病风险评估及防控策略制定的有力工具。论文介绍了流行病学模型的定义及其在动物疫病管理决策中的应用,讨论了模型的分类及建模的方法,重点阐述了动物疫病流行病学模型的构建步骤,包括建模系统和研究目标的确定、动物群体和疫病流行病学数据信息的收集、概念模型的构建、概念模型的确认、概念模型的公式化或编程、模型的验证、运行有效性的评估、敏感性分析、执行研究、输出结果的解释和交流。提出了一些建模的基本准则和应该着重考虑的问题,以期为动物疫病流行病学模型和风险评估预警研究提供参考。 相似文献
10.
The use of induced and spontaneous mutant mice and genetically engineered mice (and combinations thereof) to study cancers and other aging phenotypes to advance improved functional human life spans will involve studies of aging mice. Genetic background contributes to pathology phenotypes and to causes of death as well as to longevity. Increased recognition of expected phenotypes, experimental variables that influence phenotypes and research outcomes, and experimental design options and rationales can maximize the utility of genetically engineered mice (GEM) models to translational research on aging. This review aims to provide resources to enhance the design and practice of chronic and longevity studies involving GEM. C57BL6, 129, and FVB/N strains are emphasized because of their widespread use in the generation of knockout, transgenic, and conditional mutant GEM. Resources are included also for pathology of other inbred strain families, including A, AKR, BALB/c, C3H, C57L, C58, CBA, DBA, GR, NOD.scid, SAMP, and SJL/J, and non-inbred mice, including 4WC, AB6F1, Ames dwarf, B6, 129, B6C3F1, BALB/c,129, Het3, nude, SENCAR, and several Swiss stocks. Experimental strategies for long-term cross-sectional and longitudinal studies to assess causes of or contributors to death, disease burden, spectrum of pathology phenotypes, longevity, and functional healthy life spans (health spans) are compared and discussed. 相似文献
11.
小尾寒羊和大尾寒羊能量与蛋白质代谢规律研究 总被引：4，自引：0，他引：4
选用小尾寒羊和大尾寒羊200只．分妊娠期、泌乳期、哺乳期和生长期4个不同生理阶段．系统研究了蛋白质和能量代谢规律。研究过程采用了饲养对比试验8次．消化代谢试验16次．低氮日粮平衡试验4次，气体能量代谢试验6次．比较屠宰试验4次，并采用瘤胃瘘管技术、血液生理生化指标测定等技术。制定出小尾寒羊和大尾寒羊的能量维持需要、各级有效能转化效率、畜体总产热和绝食代谢产热等基础代谢参数89个．粗蛋白质和可消化粗蛋白质维持需要、不同生理状态和生产水平下的粗蛋白质、可消化粗蛋白质生产需要、以及内源尿氮和代谢粪氮等蛋白质代谢参数58个。 相似文献
12.
The objectives of this study were to estimate heritability for scrotal circumference (SC) and semen traits and their genetic correlations (rg) with birth weight (BRW). Semen traits were recorded for Line 1 Hereford bulls (n = 841), born in 1963 or from 1967 to 2000, that were selected for use at Fort Keogh (Miles City, MT) or for sale. Semen was collected by electroejaculation when bulls were a mean age of 446 d. Phenotypes were BRW, SC, ejaculate volume, subjective scores for ejaculate color, swirl, sperm concentration and motility, and percentages of sperm classified as normal and live or having abnormal heads, abnormal midpieces, proximal cytoplasmic droplets (primary abnormalities), bent tails, coiled tails, or distal cytoplasmic droplets (secondary abnormalities). Percentages of primary and secondary also were calculated. Data were analyzed using multiple-trait derivative-free REML. Models included fixed effects for contemporary group, age of dam, age of bull, inbreeding of the bull and his dam, and random animal and residual effects. Random maternal and permanent maternal environmental effects were also included in the model for BRW. Estimates of heritability for BRW, SC, semen color, volume, concentration, swirl, motility, and percentages of normal, live, abnormal heads, abnormal midpieces, proximal cytoplasmic droplets, bent tails, coiled tails, distal cytoplasmic droplets, and primary and secondary abnormalities were 0.34, 0.57, 0.15, 0.09, 0.16, 0.21, 0.22, 0.35, 0.22, 0.00 0.16, 0.37, 0.00 0.34 0.00, 0.30, and 0.33, respectively. Estimates of rg for SC with color, volume, concentration, swirl, motility, and percentages of live, normal, and primary and secondary abnormalities were 0.73, 0.20, 0.77, 0.40, 0.34, 0.63, 0.33, -0.36, and -0.45, respectively. Estimates of rg for BRW with SC, color, volume, concentration, swirl, motility, and percentages live, normal, and primary and secondary abnormalities were 0.28, 0.60, 0.08, 0.58, 0.44, 0.21, 0.34, 0.20, -0.02, and -0.16, respectively. If selection pressure was applied to increase SC, all of the phenotypes evaluated would be expected to improve. Predicted correlated responses in semen characteristics per genetic SD of selection applied to SC were 0.87 genetic SD or less. If selection pressure was applied to reduce BRW, the correlated responses would generally be smaller but antagonistic to improving all of the phenotypes evaluated. Predicted correlated responses in SC and semen characteristics per genetic SD of selection applied to BRW were less than 0.35 genetic SD. 相似文献
13.
中国水果资源丰富,果渣产量巨大、种类繁多、营养丰富,是良好的饲料资源。随着对果渣研究的不断深入,发现苹果渣、柑橘渣、菠萝渣、葡萄渣及沙棘果渣含有粗蛋白质（CP）、粗纤维（CF）、粗脂肪（EE）等营养成分及钙、磷、铜、锌、铁、硒、镁等矿物元素,同时还富含维生素、黄酮、多糖、多酚等活性物质,具有良好的饲用价值。然而果渣富含纤维素、木质素、果胶、单宁等抗营养物质,存在适口性差、消化率低等缺陷,影响动物消化吸收功能及对饲料的转化率。而微生物发酵可减少果渣中纤维素、木质素、植酸、果胶、单宁等抗营养成分,同时提高其粗蛋白质、氨基酸等营养物质含量,改善果渣的营养结构和营养价值,提高其利用率。研究发现,发酵果渣作为饲料可改善动物生长性能及生产性能,提高肉品质,降低养殖成本。作者总结了国内外相关研究进展,对果渣的营养价值、微生物发酵后营养变化及其发酵饲料在畜禽养殖业中的应用进行了综述,旨在阐明果渣微生物发酵饲料的应用价值、经济价值及社会价值,同时也为果渣发酵料在畜禽养殖中的深度发掘及推广提供理论参考。 相似文献
14.
JI Hui-shu LUO Guang-rong XIAO Min ZEWANG Ren-zhen ZHU Qing CHEN He-qiang ZHANG Jun-jie GUO Zheng-hong YUE Lei ZHOU Jun WEN Juan YANG Qi-yue YANG Xiao-nong 《中国畜牧兽医》2017,44(2):561-567
To understand the infection of main internal parasites in yaks, total of 402 fecal samples of yaks were collected from Hongyuan county in Aba prefecture and Litang county in Ganzi prefecture, the morphological characteristics of 4 kinds of internal parasitic eggs or oocysts were observed and the numbers of them were counted using the modified Liao's counting method. The results showed that in yaks of Hongyuan county, the average infection intensities of EPG or OPG of nematodes, cestodes, trematodes and coccidian were 11.59, 23.77, 42.45 and 14.72, respectively, and the total number of infections was 92.53 (48.91 to 154.90); The average infection rates of eggs or oocysts of these 4 kinds of parasites were 18.01%, 36.62%, 44.68% and 17.37%, respectively, and the total infection rate was 76.39%, which proved that trematodes was the dominant parasitic species and cestodes was also an important one in this area. In yaks of Litang county, the average infection intensities of EPG or OPG of nematodes, cestodes, trematodes and coccidian were 52.38, 13.10, 20.24 and 1.19, respectively, and the total number of infections was 86.90, the average infection rates of eggs or oocysts of these 4 kinds of parasites were 52.38%,19.05%,23.81% and 2.38%, respectively, the total infection rate was 78.57%, which proved that nematodes was the dominant parasitic species in this area. The infection patterns of internal parasitic eggs or oocysts in yaks in Hongyuan and Litang county were all mainly the single and double infection, the sums of these two patterns were 69.31% and 78.57%, respectively, which accounted for 90.73% and 100% of the total infection rate, respectively. The results in this paper showed that the parasitic disease in yaks was still an important disease harmful to yak production and herdsman health, meanwhile these results enriched the epidemiological data of the internal parasitic disease of yaks in Northwest plateau of Sichuan province and provided a theory basis for prevention and control of parasitic diseases in yaks in this area. 相似文献
15.
The Association of Shelter Veterinarians veterinary medical care guidelines for spay-neuter programs
Looney AL Bohling MW Bushby PA Howe LM Griffin B Levy JK Eddlestone SM Weedon JR Appel LD Rigdon-Brestle YK Ferguson NJ Sweeney DJ Tyson KA Voors AH White SC Wilford CL Farrell KA Jefferson EP Moyer MR Newbury SP Saxton MA Scarlett JM;Association of Shelter Veterinarians' Spay Neuter Task Force 《Journal of the American Veterinary Medical Association》2008,233(1):74-86
As efforts to reduce the overpopulation and euthanasia of unwanted and unowned dogs and cats have increased, greater attention has been focused on spay-neuter programs throughout the United States. Because of the wide range of geographic and demographic needs, a wide variety of programs have been developed to increase delivery of spay-neuter services to targeted populations of animals, including stationary and mobile clinics, MASH-style operations, shelter services, feral cat programs, and services provided through private practitioners. In an effort to ensure a consistent level of care, the Association of Shelter Veterinarians convened a task force of veterinarians to develop veterinary medical care guidelines for spay-neuter programs. The guidelines consist of recommendations for preoperative care (eg, patient transport and housing, patient selection, client communication, record keeping, and medical considerations), anesthetic management (eg, equipment, monitoring, perioperative considerations, anesthetic protocols, and emergency preparedness), surgical care (eg, operating-area environment; surgical-pack preparation; patient preparation; surgeon preparation; surgical procedures for pediatric, juvenile, and adult patients; and identification of neutered animals), and postoperative care (eg, analgesia, recovery, and release). These guidelines are based on current principles of anesthesiology, critical care medicine, microbiology, and surgical practice, as determined from published evidence and expert opinion. They represent acceptable practices that are attainable in spay-neuter programs. 相似文献
16.
选择安徽淮南乳品公司为试验试点,随机抽取荷斯坦奶牛472头(1~≥6胎)进行隐性乳房炎与乳房性状相关性分析,测定的乳房性状主要包括前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置和乳头长度。结果表明:淮南地区荷斯坦奶牛隐性乳房炎的乳区阳性率和奶牛阳性率分别为25.79%和53.18%;乳房性状前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置、乳头长度的线性评分分别为31.92分、47.02分、29.00分、37.64分、20.02分、39.74分、20.88分。隐性乳房炎的乳区阳性率与前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置、乳头长度的表型相关系数分别是-0.0731、0.0211、0.1003、-0.0369、0.0996、-0.0323及-0.0151,其中与后房宽度、乳房深度为显著(P<0.05)的正相关,其余均未达到显著水平(P>0.05);奶牛阳性率与前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置、乳头长度的表型相关系数分别为-0.0427、0.0680、0.0347-、0.0060、0.1071、-0.0119和0.0223,除与乳房深度为显著(P<0.05)的正相关外其余均不显著(P>0.05)。 相似文献
17.
NaCl胁迫对藜麦种子萌发和幼苗生理特性的影响 总被引：4，自引：0，他引：4
本研究报道了不同浓度NaCl处理对藜麦种子萌发及幼苗生理特性的影响,以确定藜麦的耐盐阈值,为藜麦在盐渍土地种植提供理论依据。结果表明,不同浓度NaCl处理对藜麦种子萌发和幼苗生理特性均产生显著影响,主要表现为,1)随着NaCl浓度的升高,藜麦种子的发芽率、发芽势、发芽指数和活力指数均呈逐渐降低的趋势,当NaCl浓度达到3.0%时,藜麦种子几乎不发芽;2)幼苗叶片含水量逐渐降低,可溶性糖、脯氨酸、丙二醛含量、相对电导率及O2-·产生速率呈逐渐升高的趋势,叶绿素含量、超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性在NaCl浓度为1.8%时达到最大值,而后随着NaCl浓度的升高呈降低的趋势;3)NaCl胁迫显著抑制了藜麦幼苗株高、茎粗的增加,根长的生长随着NaCl浓度的升高呈先增加后减少的趋势,在NaCl浓度为1.8%时根长最长,达到11.73 cm。说明低浓度(≤1.8%)NaCl处理对藜麦幼苗生长具有促进作用,而高浓度的NaCl处理则对其有抑制作用。藜麦耐盐阈值为1.8%。 相似文献
18.
19.
以葡萄品种‘玫瑰蜜’为试材,通过对主干进行一次和二次环剥,研究了对其果实大小、果皮色素、果肉营养物质含量及其形成规律的影响。结果表明,在果实成熟过程中,果皮叶绿素、可滴定酸的含量均逐渐降低,类胡萝卜素、花色苷、总酚、总黄酮及果实各种营养物质含量均逐渐上升,而淀粉和钾的含量则先升高后降低。环剥不仅能够显著提高果皮类胡萝卜素、花青苷、总酚、总黄酮和果汁可溶性固形物的含量,而且还能显著降低果汁可滴定酸、维生素C的含量,增加固酸比。环剥后,果实可溶性糖、葡萄糖、可溶性蛋白质、总氮、磷和钾的含量均显著升高,而铁、锌和铜的含量则显著降低。此外,二次环剥显著增大了单果重、果实纵径和横径,而一次环剥则使其显著降低。主干一次和二次环剥均能显著提高玫瑰蜜葡萄的果实品质,在生产上,若用于鲜食可进行二次环剥,若用于酿酒则仅需一次环剥即可。 相似文献
20.
Aupperle H März I Thielebein J Dinges G Schoon HA 《Veterinary journal (London, England : 1997)》2010,183(2):176-183
The histomorphological findings and immunohistochemical expression of matrix metalloproteinases (MMPs-1, 2, 9 and 14) and their tissue inhibitors (TIMPs-2, 3 and 4) are reported in the parietal (pTV) and septal leaflets (sTV) of the tricuspid valves in normal dogs and dogs with chronic valvular disease (CVD). The layers of the normal sTV were not as well defined as in the pTV and the spongiosa of the sTV contained abundant mucopolysaccharides (MPS) and adipocytes. In CVD, there was expansion of the spongiosa of the pTV due to deposition of MPS, leading to formation of nodules along the free edge. In CVD, there was fibrosis of the atrialis of the sTV and formation of nodular deposits of MPS in the spongiosa and ventricularis, mainly affecting the proximal and middle parts of the leaflet. In dogs with normal pTV and sTV, MMPs-1 and 14 and TIMPs-2, 3 and 4 were expressed, while MMPs-2 and 9 were absent. In mild CVD, expression of MMPs-2, 9 and 14 were increased in the pTV, whereas small foci within the spongiosa contained MMP-9 and TIMP-3 positive cells. In advanced CVD, MMP-14 also was increased in the pTV. In mild CVD, there was increased expression of MMPs-1 and 2 and TIMP-2, but decreased expression of TIMP-4, in the sTV. Small foci with expression of MMP-14 and TIMPs-2, 3 and 4 were also present in the sTV in mild CVD. In advanced CVD, there was increased expression of MMPs-2 and 9 and TIMP-2 in the sTV. In CVD there is upregulation of various MMPs in the pTV, whereas there is a complex alteration in expression of MMPs and TIMPs in the sTV. 相似文献