Landscape context mediates influence of local food abundance on wetland use by wintering shorebirds in an agricultural valley

While it is widely understood that local abundance of benthic invertebrates can greatly influence the distribution and abundance of wetland birds, no studies have examined if wetland landscape context can mediate this relationship. We studied the influence of wetland food abundance and landscape context on use of agricultural wetlands by wintering dunlin (Calidris alpina) and killdeer (Charadrius vociferus) in the Willamette Valley of Oregon, USA, over two winters (1999-2000, 2000-2001) of differing rainfall and subsequent habitat distribution. We monitored bird use (frequency of occurrence and abundance) at a sample of wetlands differing in local food abundance (density and biomass) and landscape context [adjacent shorebird habitat (defined as ha of wet habitat with less than 50% vegetative cover and within a 2-km radius) and nearest neighbor distance]. We evaluated predictive models for bird use using linear regression and the Cp criterion to select the most parsimonious model. During the dry winter (2000-2001), dunlin exhibited greater use of sites with higher invertebrate density and biomass but also with more adjacent shorebird habitat and closest to a wetland neighbor. However, neither landscape context nor food abundance were important predictors of dunlin use during the wet winter (1999-2000). Use of sites by killdeer was unrelated to either local food abundance or landscape context measures during both winters. Our findings contribute to a growing recognition of the importance of landscape structure to wetland birds and highlight a number of implications for the spatial planning and enhancement of wetlands using a landscape approach.     

珠防工程幼林综合持水能力研究

本文在对珠防工程监测样地调查、测定的基础上,从林冠层、枯落物层和土壤层3个水文层次对珠防二期工程幼林的综合持水能力进行了评价.3 a～4 a生珠防林幼林的综合持水量在2355.25～2457.08 t/hm2之间,比荒山高3.7%～8.2%.其中土壤贮水量、枯落物持水量、植冠层的持水量分别比荒山高3.65%～8.03%、21.4%～61.1%和42.9%-305.3%,而土壤贮水量、枯落物持水量增加不明显,植冠层持水量增加显著.植冠层和枯落物层的持水量比土壤持水量小得多,林分的贮水主体为林地土壤.珠防林幼林的综合持水能力因恢复措施以及林分类型不同而存在差异.人工造林幼林的综合持水能力比封山育林高;4 a生的针叶林的综合持水量最大,针阔混交林、竹林次之;3 a生的阔叶林的综合持水量最大,针阔混交林、针叶林次之.     

猪瘟病毒、猪繁殖与呼吸障碍综合征病毒和乙型脑炎病毒多重RT-PCR检测方法的建立

根据猪瘟病毒(CSFV)的E2基因保守序列、猪繁殖与呼吸障碍综合征病毒(PRRSV)的ORF7基因及部分ORF6和3-UTR基因序列和猪乙型脑炎病毒(JEV)的E基因保守序列,设计了3对引物,扩增大小分别为288 bp、430 bp和1 015 bp目的片段.以纯培养病毒抽提RNA,制备cDNA模板,利用3对引物,通过条件的优化,建立了同时检测这3种病毒的多重RT-PCR.CSFV、PRRSV和JEV的RNA最小检出量分别为0.270 ng、0.049 ng、0.067 ng,其它的RNA病毒如TGEV以及DNA病毒如PPV、PrV、PCV-2检测结果为阴性.以β-actin为对照,利用本方法检测了174份临床样品(血清、肺脏和胎儿),其结果为:PRRSV、CSFV和JEV的阳性率分别为30.4%、4.6%和1.7%;CSFV和PRRSV混合感染阳性率为1.7%.同时对临床样品中CSFV、JEV和PRRSV阳性PCR产物进行测序分析,发现CSFV、PRRSV和JEV的PCR产物序列和NCBI数据库中目标基因的同源性分别为92%、90%和89%,这证实了多重PCR的阳性结果为上述3种病毒.结果证明,所建立的多重RT-PCR可用于临床检测.     

猪瘟病毒化学发光抗体检测方法的建立与应用

旨在建立猪瘟病毒(CSFV)化学发光抗体检测方法,本研究以CSFV E2蛋白作为包被抗原,山羊抗猪IgG-HRP抗体作为酶标抗体,鲁米诺为底物溶液,优化检测方法,成功建立CSFV化学发光抗体检测方法.该方法能在室温20 min内完成对CSFV抗体血清特异性检测,灵敏度与商品化CSFV抗体检测试剂盒相当,且与A型口蹄疫病...     

非洲猪瘟形势下我国养猪业该何去何从

非洲猪瘟是由非洲猪瘟病毒感染家猪或野猪后引发的一种恶性传染病,该疫病在中国的暴发给整个养猪业造成了毁灭性的打击。然而,目前虽有报道称已经有科研单位研制出非洲猪瘟疫苗,但距离其实际应用于生产仍需要相当长的时间。中国是全球最大的猪肉生产和消费国,非洲猪瘟疫情在我国的快速传播使我国生猪产能遭受重创,直接导致猪肉供求失衡、猪肉价格翻番、猪肉市场异动。因此,文章从非洲猪瘟的传播方式、对非洲猪瘟相对有效的防控措施等方面探讨在非洲猪瘟形势下我国养猪业该如何维持产能、如何走好养殖之路。     

评定菜籽粕的肉鸭净能的研究

本试验旨在实测菜籽粕的肉鸭净能(NE),并通过相关、回归分析建立菜籽粕NE与其常规组分之间的回归模型。试验采用析因法将菜籽粕的NE剖分为其提供给肉鸭的维持净能(NEm)和沉积净能(NEp),NEm用肉鸭禁食产热(FHP)来估计,NEp用比较屠宰法测定。选用760只7日龄、平均体重为(130.48±3.01)g的樱桃谷肉鸭进行试验:首先选择100只肉鸭进行NEm评定试验,设自由采食、限饲15%、限饲25%、限饲35%和限饲45%共5个处理,建立产热(HP)和食入代谢能(MEI)的回归关系,外推到MEI为0时求得FHP;然后选择640只鸭进行NEp评定试验,试验前屠宰20只肉鸭测定初始体能量作为起始对照,设基础饲粮组和菜籽粕替代基础饲粮组31个处理,所有处理均设5个重复,每个重复4只肉鸭,15日龄时将肉鸭全部屠宰测定体能量;最后将菜籽粕NE与其常规组分进行相关、回归分析并建立预测模型。结果表明:1)樱桃谷肉鸭的NEm为0.557 MJ/(kg W0.75·d)。2)31种不同菜籽粕的NE有较大差异,经套算法得到菜籽粕的NE为4.18~6.05 MJ/kg DM,NE/表观代谢能(AME)为0.56±0.06。3)菜籽粕NE与其常规组分高度相关,多元线性逐步回归建立的回归模型如下:NE=0.416 AME+0.041 CP-0.020 NDF+0.110 CF-1.093(R2=0.901,RSD=0.06,P0.01),式中:CP为粗蛋白质,NDF为中性洗涤纤维,CF为粗纤维。由此可见,不同来源的菜籽粕的常规组分和肉鸭NE有较大差异,菜籽粕NE与其常规组分高度相关,并具有回归关系。     

猪瘟病毒E2基因噬菌体展示多肽库的构建及表位鉴定

本研究通过建立CSFV噬菌体展示多肽库,并对其进行生物淘选,以期获得E2蛋白上新的抗原表位.选择CSFV石门株(SM)和疫苗株(HCLV)为代表株,采用噬菌体展示技术,以T7select415-1b为载体,分别构建了CSFV SM株和HCLV株E2基因噬菌体展示多肽库(SM-E2库和HCLV-E2库).通过生物淘选和噬菌体原位杂交技术,采用7株猪瘟单克隆抗体和1株猪瘟高免血清分别对构建的SM-E2库和HCLV-E2库进行抗原表位筛选.结果共筛选到了5条与E2蛋白高度同源的序列,在E2蛋白上的同源区域分别为TAVSPTTLR、YYEP、TTWKEYSH、GGQ(V)VK和PDGLPHY.结果表明,TAVSPTTLR、YYEP和TTWKEYSH序列与目前已知E2蛋白表位一致,说明它们是E2蛋白上的优势表位;GGQ(V)VK和PDGLPHY序列与预测表位一致,推测是E2蛋白上潜在的抗原表位.     

抗猪瘟IgY的制备及临床应用初报

应用合理的免疫程序,用猪瘟抗原免疫蛋鸡,并以水稀释法、聚乙二醇萃取法结合透析对所产蛋的卵黄部分进行处理,成功地提取到抗猪瘟IgY(SF-IgY),获得率为6.83mg/mL。该制剂纯度为45.14％,能中和1000MID猪瘟兔化种毒,用于紧急治疗猪瘟后,临床应用效果确实。     

Pestivirus infections in Norway. Serological investigations in cattle, sheep and pigs.

Serum samples from 1,133 dairy cows (187 herds), 3,712 ewes (103 flocks) and 1,317 adult pigs (877 herds), were tested for neutralizing antibodies against the NADL strain of bovine virus diarrhoea virus. The prevalence rate of seropositive animals was 18.5% in cattle, 4.5% in sheep and 2.2% in pigs, such seroreactors being found in 28% of the cattle herds and 18% of the sheep flocks. In all three species the rate showed considerable herd and geographical variation. In cattle the seroreactor rate was similar in herds with normal reproduction and in 62 herds with problems of repeat breeding. Of 31 pig sera containing antibodies against the NADL strain, 27 were also positive in a neutralization test for antibodies against swine fever virus (Baker strain). However, all sera showed a higher titre of antibodies against the bovine strain than against the swine fever virus. It was concluded that the immune response of the pigs had been induced by ruminant pestivirus, and not by swine fever virus.