Methods to determine resistance to anthelmintics when continuing larval development occurs

The in vivo faecal egg count reduction test (FECRT) is the most commonly used test to detect anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) of ruminants in pasture based systems. However, there are several variations on the method, some more appropriate than others in specific circumstances. While in some cases labour and time can be saved by just collecting post-drench faecal worm egg counts (FEC) of treatment groups with controls, or pre- and post-drench FEC of a treatment group with no controls, there are circumstances when pre- and post-drench FEC of an untreated control group as well as from the treatment groups are necessary. Computer simulation techniques were used to determine the most appropriate of several methods for calculating AR when there is continuing larval development during the testing period, as often occurs when anthelmintic treatments against genera of GIN with high biotic potential or high re-infection rates, such as Haemonchus contortus of sheep and Cooperia punctata of cattle, are less than 100% efficacious. Three field FECRT experimental designs were investigated: (I) post-drench FEC of treatment and controls groups, (II) pre- and post-drench FEC of a treatment group only and (III) pre- and post-drench FEC of treatment and control groups.To investigate the performance of methods of indicating AR for each of these designs, simulated animal FEC were generated from negative binominal distributions with subsequent sampling from the binomial distributions to account for drench effect, with varying parameters for worm burden, larval development and drench resistance. Calculations of percent reductions and confidence limits were based on those of the Standing Committee for Agriculture (SCA) guidelines. For the two field methods with pre-drench FEC, confidence limits were also determined from cumulative inverse Beta distributions of FEC, for eggs per gram (epg) and the number of eggs counted at detection levels of 50 and 25. Two rules for determining AR: (1) %reduction (%R) < 95% and lower confidence limit <90%; and (2) upper confidence limit <95%, were also assessed. For each combination of worm burden, larval development and drench resistance parameters, 1000 simulations were run to determine the number of times the theoretical percent reduction fell within the estimated confidence limits and the number of times resistance would have been declared.When continuing larval development occurs during the testing period of the FECRT, the simulations showed AR should be calculated from pre- and post-drench worm egg counts of an untreated control group as well as from the treatment group. If the widely used resistance rule 1 is used to assess resistance, rule 2 should also be applied, especially when %R is in the range 90 to 95% and resistance is suspected.     

青海省草地资源保护与利用存在问题及发展思路

草地资源是青海畜牧业经济持续发展的物质基础,是青藏高原的天然屏障,是生物多样性的基因库,是牧民群众生存的基础。本文结合青海省草地资源保护与利用现状及存在突出问题,客观、科学的提出了加强宣传教育,调整产业结构,加强设施建设,健全法规制度等促进草地资源保护与利用的有效途径。     

若尔盖高寒沼泽与草甸中脊椎动物分布规律浅析

描述了若尔盖高寒沼泽中脊椎动物的分布规律，沼泽脊椎动物分布受多种因素制约和影响，因而有关多样化分布的适应性与生活型，沼泽，草甸与共生脊椎动物可随外界环境与行为的影响和干扰而发生变化。在不利于沼泽，草甸的人为活动影响下，淄泽，草甸，动物自馈生态系统受到冲击，脊椎动物及其载体共生体系便会变得更加脆弱。如任其发展并失去有效控制，即会造成沼泽及其上脊椎动物及其载体共生体系便会变得更加脆弱，如任其发展并失去有效控制，即会造成沼泽及其上脊椎动物不可逆转的毁灭性消亡或大迁徙。     

中国结缕草属(Zoysia spp.)植物抗寒性评价

在广泛收集结缕草属(ZoysiaWild.)种质资源基础上,按照形态类型和地理分布,选取40份种质,采用电导法(EL)对其抗寒性进行初步评价。以半致死温度(LT50)为评价指标,在参试材料中除大穗结缕草和来自台湾岛海边沙地的沟叶结缕草外,其它种质都较天堂-419(对照)抗寒;在结缕草属内,抗寒性具有明显的种间差异,耐寒性依次为日本结缕草>中华结缕草>沟叶结缕草>细叶结缕草>长花中华结缕草>大穗结缕草,其中细叶类型的沟叶结缕草和细叶结缕草抗寒性变异较大;日本结缕草和中华结缕草抗寒性变异与地理分布之间没有显著关系,但分布在海边的种类和种质抗寒性明显较低;结缕草属及其中华结缕草的抗寒性与叶长、叶宽以及叶背面被毛之间均存在显著的负相关关系,但这种关系不体现在日本结缕草上。实验结果还表明,EL方法是评价结缕草属抗寒性较为可靠的方法之一。     

云和雪梨种质资源和栽培技术现状分析

云和雪梨是浙江丽水传统名果,是一系列的砂梨地方品种,具有果大、晚熟和质优的特点。云和雪梨种质资源丰富,初选的优良单株较多,然而由于栽培品种混杂、配套栽培技术和贮藏技术不成熟等原因,云和雪梨品种选育进程和产业发展滞缓,每年的产量不能满足本地消费需求。本文结合文献和实地调查,综述了云和雪梨种质资源评价和研究、品种选育及栽培技术等方面的现状和问题,并提出了相应的对策,为云和雪梨品种选育和产业发展提供参考。     

中国奶牛养殖生产布局时空演变分析

本研究基于2001—2017年中国奶牛存栏量统计数据,运用奶牛养殖布局指数、奶牛养殖重心模型和空间自相关模型分析方法,分析中国奶牛养殖生产布局在时间和空间上的演变过程和特征。结果表明:①东北和内蒙古产区奶牛存栏量呈下降趋势,华北产区保持稳定上升,西部产区缓慢上升,南方产区和大城市周边产区呈下降趋势;内蒙古、新疆和黑龙江稳居奶牛养殖主产区的主导地位,但优势逐渐减弱,以河南为代表的新兴产区奶牛养殖发展迅速。②奶牛养殖重心呈现出先向东南方向移动再向西南方向移动的演变趋势。③省际间奶牛存栏量具有全局空间正相关性且相关性不断增强,并已在黑龙江、山西、贵州、广东、海南、云南、广西、河南、陕西、青海、吉林、辽宁和河南出现局部地理集聚现象。最后,提出促进我国奶业发展的相关建议。     

云南省昆明市动物园大肠杆菌分离株毒力基因分布特征

为研究云南省昆明市动物园动物体内大肠杆菌(E.coli)分离株毒力基因的分布特征,从圆通山动物园37个动物种群粪便中分离出37株E.coli,采用生化鉴定方法鉴定大肠杆菌,PCR方法检测19种毒力基因。鉴定结果表明:37株E.coli中,ompA、iroN、fimC、aatA、vat 5种毒力基因携带率分别为100%、95.49%、83.78%、70.27%、51.35%,ibeA、neuC、iutA、traT、stx 5种毒力基因携带率为0,其他9种毒力基因携带率均低于40.00%;分离菌株普遍携带8种以下毒力基因,同时携带10种以上毒力基因的概率为8.10%;分离株强毒力岛基因携带率较高,分布较为普遍。结果表明,昆明市圆通山动物园内流行的大肠杆菌以致病性大肠杆菌为主,不同种类动物体内大肠杆菌的毒力基因携带率存在较大差异,其原因可能与动物的饲养环境以及动物自身的适应能力和抵抗力有关。因此,对于动物园内具有较高大肠杆菌致病风险的动物,要采取相应防治措施,防止大肠杆菌病发生与流行。     

茶及其副产品在畜禽养殖中的应用

我国茶资源丰富,且其富含多种独特的营养成分,可以调节畜禽机体的生理功能,在畜禽养殖应用中无残留、无毒副作用,能从根本上满足人们对畜禽产品品质安全的需求,从而改善和提高人们的生活水平。为此,文章就茶及其副产物的生物学特征和营养水平进行介绍,并综述其作为饲料资源对畜禽自身的生长发育、畜产品品质的影响,以及在畜禽养殖上的保健作用,旨在为茶及其副产物作为新型饲料资源的开发应用提供参考。     

蒲公英内生真菌PG23抗癌活性的初步研究

研究药用植物蒲公英内生真菌PG23多糖对肺癌A549细胞的抑制作用。蒲公英内生真菌PG23通过培养,乙醇沉淀获得粗多糖、苯酚-硫酸法测定多糖含量,采用MTT法测定PG23多糖对肺癌A549细胞的抑制率,并计算半抑制浓度(IC50)。结果表明,PG23发酵液中多糖得率为2.754%,多糖含量为26.82%;对A549肺癌细胞的抑制率以第1天为最高;抑制率不与多糖浓度成比例,最佳作用浓度为14.42μg/mL,抑制率为87.63%(P<0.01),IC50为1.073mg/mL(24h)。PG23发酵液多糖对肺癌A549细胞具有较强的抑制能力。     

江河源区草地资源现状及其可持续发展

在分析青海省江河源区草地资源现状的基础上，进一步剖析了造成该区域草地生态环境恶化的综合因素，提出了合理利用和保护天然草地，优化草地生产结构，加强基础设施建设，建立饲草料生产基地，遏制草地退化，使草地生态进入良性演替，实现江河源区草地资源可持续利用和草地畜牧业可持续发展的对策。