Identification and molecular characterization of border disease virus (BDV) from sheep in India

Pestiviruses isolated from sheep and goats in India thus far have been bovine viral diarrhoea virus 1 (BVDV-1) or BVDV-2. During routine genetic typing of pestiviruses in the years 2009-10, border disease virus (BDV) was detected in eight Indian sheep of a flock showing clinical signs of BD by real time RT-PCR. All the samples yielded positive virus isolates in cell culture but were found negative by a BVDV antigen ELISA. A representative BDV isolate was characterized at genetic and antigenic level. Phylogenetic analysis carried out in 5′-UTR, N^pro and E2 regions of genome typed the Indian BDV isolate as BDV-3. A more detailed analysis in N^pro and entire region coding structural proteins showed that the N^pro (168), C (100 aa), E^rns (227 aa), E1 (195 aa) and E2 (373 aa) proteins were of size characteristic for BDV reference strain X818. Antigenic differences were evident between the BDV-3 isolate and previously reported BDV-1, BDV-5 and BDV-7 strains. Although origin of BDV-3 in India is not clear, the results reflect probable introduction through trade in sheep between India and other countries or BDV-3 may be more widely distributed. Additionally, this study suggests that for diagnosis of BDV infection, the commercial BVDV Ag-ELISA should be used with caution. This is the first identification of BDV in sheep in India which highlights the need for continued pestivirus surveillance and assessing its impact on sheep and goat production.     

Seroprevalence,associated risk factors analysis and first molecular characterization of chlamydia abortus among Egyptian sheep

Chlamydia abortus is one of the most common abortive agents worldwide in sheep. Few studies have been reported C. abortus infection among sheep in Egypt but the available data is scarce. The objective of the present study was to determine the seroprevalence of C. abortus among sheep, the associated risk factors and its molecular characterization. The present study was conducted on 675 sheep in six Governorates at Northern Egypt. Data analysis confirmed the presence of antibodies against C. abortus in 93 out of 675 sheep. The logistic regression model was fitted to identify the associated risk factors with C. abortus infection. The results revealed that C. abortus increased significantly in ewes (OR = 4.04, 95 %CI: 1.44−11.28) during autumn season (OR = 3.6, 95 %CI: 1.64–8.28), in ewes with a history of abortion (OR = 1.4, 95 %CI: 0.87–2.50) and in farm where no lambing pen (OR = 2.2, 95 %CI: 1.30–3.94) or abscence of post abortion measures (OR = 1.96, 95%CI: 1.23-3.12). In addition, age, flock size and exchange of breeding ram had no significant effect on prevalence of chlamydiosis. Also, PCR assay was confirmed presence of C. abortus as accusative pathogen in aborted ewe and the genetic characterization of Egyptian C. abortus strain revealed 100 % identity with another strain from Iraq. A control program should be applied to reduce economic losses and risk of human infection.     

Demography,population dynamics and sustainability of the Patagonian sheep flocks

Sheep production is the main agricultural activity in Patagonia. Since the middle of the 20th century, sheep numbers have declined steadly. We used historical records of stock numbers in four ranches to analyze the importance of regional factors so as to explain the decline of the Patagonian sheep flocks. We found that the stocks of all the four ranches declined with a similar trend but fluctuated independently, thus reflecting a complex interaction between regional and local factors. Aboveground net primary production (ANPP) and vegetation physiognomy explained most of the differences in the flocks declining rates. We estimated demographic parameters for two ranches differing in their average annual growth rates. From these demographic parameters, we constructed deterministic and stochastic matrix models to establish the relative contribution of demographic processes to the observed decline. Matrix models projected a faster decline than that observed in the ranch used to calibrate the model. This suggests that the recorded demographic parameters could drive most stocks to extinction in less than 100 years. We concluded that the observed dynamics would be generated by demographic processes, but extinction is delayed or avoided by a continuous intake of animals. Ewe survival was the most important parameter in controlling the growth rate of the flocks. The environmental stochastic model showed that the growth of the stocks was highly sensitive to increases in the frequency of good years (those that produce a positive growth) and in the transition from normal years to bad years. All these evidences point out the existence of biological constraints to sheep production in Patagonia: ANPP and vegetation structure would control flock population dynamics throughout its effects on key demographic parameters, ewe survival and marking rate (a recruitment measure). Our model results suggest that the decline in sheep numbers, and hence the sustainability of the activity, is driven, to a large extent, by the demographic characteristics of the flocks.     

剪羊毛机剪头振动参数的测试研究

剪羊毛机剪头的振动属扭转振动，通过理论分析和测试，对剪羊毛机剪头及剪头各主要工作部件在工作中的扭振或激励进行了研究，这对研究剪羊毛机剪头的振动、减振降噪及改善其荼性能等均有重要意义。     

用绵羊小肠液冻干粉测定饲料过瘤胃淀粉小肠消化率方法的研究

本试验旨在以玉米为样本筛选用绵羊小肠液冻干粉测定精饲料瘤胃非降解残渣淀粉小肠消化率的最佳培养条件。分别研究了小肠液冻干粉用量(0.2、0.3、0.4、0.5和0.6g)对16h玉米瘤胃非降解残渣干物质和淀粉小肠消化率的影响;离体培养时间(4、8、12、16、20和24h)对16h玉米瘤胃非降解残渣干物质和淀粉小肠消化率的影响。结果表明,在本试验条件下,绵羊小肠液冻干粉测定玉米瘤胃非降解残渣淀粉小肠消化率的最佳用量为0.45g小肠液冻干粉/0.56g玉米瘤胃非降解残渣,最佳培养时间为12h。利用绵羊小肠液冻干粉测定常用饲料过瘤胃残渣淀粉小肠消化率的方法是可行的。     

绵羊PRKAG3基因SNPs与肉质性状的相关性分析

为从分子水平研究甘肃境内典型养殖模式下甘肃高山细毛羊、小尾寒羊、藏羊、蒙古羊和滩羊5个绵羊品种的PRKAG3基因多态性与屠宰性能和肉品质的相关性,探讨以PRKAG3为候选基因,提高绵羊屠宰性能和肉品质的可能性。采用PCR-SSCP技术对5个绵羊品种的PRKAG3基因外显子4,5和内含子4多态性进行检测,并就PRKAG3基因多态性与9月龄屠宰性能和肉品质进行相关性分析。结果表明,在PRKAG3基因2 689 bp处发生了AG的突变,位于第4内含子第23 bp处,表现出3种基因型,AA、AB和BB。纯合度(Ho)分别为0.67,0.69,0.76,0.69,0.59,杂合度(He)分别为0.333 3,0.306 1,0.244 9,0.307 7,0.408 2,有效等位基因(Ne)分别为1.62,1.66,1.69,1.48,1.79,多态信息含量(PIC)分别为0.31,0.32,0.33,0.27,0.34。除藏羊外其他4个绵羊品种均处于Hardy-Weinberg平衡状态。关联分析表明,5个绵羊品种PRKAG3基因此变异位点的3个基因型间失水率性状差异显著(P0.05);BB基因型个体的胴体重显著高于AA型(P0.05),滩羊为极显著(P0.01),BB基因型个体的眼肌面积显著大于AA型(P0.05)(藏羊除外)。因此说明PRKAG3基因可作为候选基因用于绵羊产肉性能和肉品质的分子标记辅助选择。     

绵羊对4种蛋白饲料日粮营养物质消化动态变化的比较

试验采用3头35 kg左右的美利奴绵羊研究不同蛋白饲料日粮对绵羊营养物质消化的影响。为自身对照试验设计,整个试验分4期进行,每期3头羊饲喂同一种蛋白饲料日粮。4种蛋白来源分别为棉籽粕、大豆粕、葵粕和菜籽粕。试验结果表明:绵羊采食蛋白来源为棉籽粕的日粮时,干物质、有机物和氮采食量最高,而菜籽粕采食量最低。饲喂棉籽粕日粮,干物质、有机物和纤维素十二指肠流量显著高于大豆粕日粮和菜籽粕日粮(P<0.05)。大豆粕日粮粗蛋白在前胃的消失率最高为33%,其余3组日粮粗蛋白前胃的降解率为16%~20%。到达小肠的菌体蛋白(MCP)量各组间无差异,而到达小肠过瘤胃饲料蛋白的量(率)棉籽粕组显著高于葵粕组、菜籽粕组、大豆粕组。大豆粕组粗蛋白在小肠的表观消化率最低为48%,其余3组日粮粗蛋白小肠表观降解率均为66%。     

新疆绵羊致病株李氏杆菌种型鉴定与分析

采用生化反应、溶血试验、致病力试验和PCR方法对分离的新疆5株绵羊致病株李氏杆菌90SB1、90SB2、90SB5、90SS1和125SL进行了种的鉴别测定,并用RAPD技术对这5株李氏杆菌及标准株李氏杆菌进行了初步分型。结果表明,5株绵羊致病株(野毒株)在生化反应、培养特性、溶血性、致病性及溶血素基因特异性等方面表现高度的一致性,属于同一种LM。RAPD实验表明这5株LM指纹图谱相同,属于同一个型。而且其致病性LM与标准LM对照株(从食品中分离到)指纹图谱差异显著,属于不同型。     

复合纳米抗菌肽防治羊皮下脓肿病的效果

抗菌肽具有抗菌谱广、不易产生耐药性、无残留等优点,而金黄色葡萄球菌是羊和兔皮下脓肿病的主要病原菌之一。通过对羊皮下脓肿组织样本分离到的金黄色葡萄球菌进行体外抗菌肽抑菌活性检测,同时建立试验兔金黄色葡萄球菌皮下脓肿模型,使用抗菌肽进行防治,最后在羊场开展抗菌肽防治羊皮下脓肿病的试验。结果发现抗菌肽对金黄色葡萄球菌的最小抑菌浓度为3 900μg/mL,抑菌圈直径达到40 mm,抗菌效价U=1.3×10⁷。试验兔防治试验发现,预防组：预防性饲喂抗菌肽能避免金黄色葡萄球菌皮下脓肿病的发生;治疗组：饲喂抗菌肽可使致病后的试验兔14 d内康复。抗菌肽防治羊皮下脓肿病发现,预防试验：预防组发病率为0.6%(n=834),而对照组发病率为12.4%(n=780);治疗试验：发病后采用抗菌肽结合简单外科手术治疗,14 d内治愈率达95.5%(n=110),3个月内复发率为0,而未用抗菌肽,仅采用简单外科手术治疗,14 d内治愈率为36.4%(n=110),3个月内复发率为77.3%(n=110)。说明抗菌肽具有较好的防治羊皮下脓肿病的效果。