塔落岩黄芪、细枝岩黄芪及其变异型的生理特性研究

本文研究了毛乌素沙漠地区塔落岩黄芪和细枝岩黄芪及其变异型的生理学特性。结果表明,塔落岩黄芪和细枝岩黄芪各与其变异型之间在生理特性方面存在着极其显著的差异。     

科尔沁草地的畜草平衡与草业发展途径的研究

根据实地调查和历年的统计资料，系统分析研究了科尔沁草地多年来草业发展速度落后于牲畜增长速度、畜草供需严重失衡的现状。结果表明，草地退化４５．９％，超载率达３６．１％。该地区发展草业的自然和社会经济条件优越，但必须采取以下措施才能达到畜草平衡的目的：加强合理利用和改良天然草地；发展人工饲草料基地，迅速增加种植畜牧业比例；大力发展秸秆及农副产品饲草料加工业     

畜禽遗传资源保存的计算机模拟研究

运用计算机模拟方法产生畜禽品种的模拟保种群体,进行畜禽群体的保种研究。笔者考虑了选择、群体有效含量、性状的遗传力水平、控制性状的基因效应以及基因位点间的连锁强度等共24个参数组合,每种参数决定一个模拟群并且重复5次,共产生120个模拟群体,实验进行50世代。由模拟群体所得结果,讨论群体以及不同基因效应模型下群体生产性能均值、近交系数、基因丢失和群体基因频率等的变化,为实际畜禽保种工作提供理论依据。     

Technical note: Development of an enzyme-linked immunosorbent assay for the determination of florfenicol and thiamphenicol in swine feed

One polyclonal antibody against florfenicol and thiamphenicol was produced and a competitive ELISA was developed for the detection of florfenicol and thiamphenicol in swine feed. The ELISA gave a 50% inhibiting concentration of 1.02 ng/mL for florfenicol. For swine feed fortified with 0.05 to 3.0 mg/kg, the interassay recoveries of florfenicol and thiamphenicol ranged from 86.4 to 118.6%, whereas intraassay recoveries of both drug ranged from 90.1 to 126.5% with less than 15% CV. Results obtained from HPLC-tandem mass spectrometry indicated this ELISA procedure could be used as a convenient method for rapid screening of florfenicol and thiamphenicol in swine feed.     

桑蚕卵电晕人工孵化技术研究：V.电晕处理蚕种的农村饲育

通过１９９４～１９９６年电晕处理蚕种的农村饲养，得到以下几点认识，在保证卵面消毒和排除孵化不齐因素情况下，电晕蚕种与浸酸蚕种的产量质量无显著差异，专供农用的大板电晕仪存在放电不匀，孵经不齐和孵化率欠高的问题，有待改进，电晕处理蚕种还须进行卵消毒。     

家蚕有滞育多化性品种滞育卵复式冷藏继代法的研究

利用上年中秋制种的滞育卵经复式冷藏处理,到当年夏蚕期饲养,夏制种再经中秋蚕期饲养,进行了有滞育多化性品种的省力保种试验.夏蚕期其生命力较对照组低1.2%~1.9%,生种率上升16.0%,差异达显著程度.中秋蚕期生命力高1.0%,生种率低0.9%,完全恢复正常.重复试验,结果一致.有滞育多化性品种用滞育卵复式冷藏处理一年二次省力保种是可行的.     

热敏电阻冰点仪法测定生鲜牛乳中冰点的研究

利用热敏电阻冰点仪法测定生鲜牛乳中的冰点,对该方法的重复性、灵敏度以及掺水掺盐对生鲜牛乳冰点值的影响等方面进行了研究.此方法的检测极限值为2.4 m℃.     

Multiple amino acid substitutions are involved in the adaptation of H9N2 avian influenza virus to mice

To explore adaptation of avian influenza virus to mice we previously performed serial lung-to-lung passages of the influenza A/Chicken/Jiangsu/7/2002 (H9N2) strain, resulting in the isolation of a variant influenza strain lethal for mice. We now report that virulence correlates with improved growth characteristics on mammalian cells and extended tissue tropism in vivo. Sequencing of the complete genomes of the wild-type and mouse-adapted viruses revealed 25 amino acid substitutions. Some were found to reiterate known substitutions in human and swine H9N2 influenza isolates. Functions affected include nuclear localization signals and sites of protein and RNA interaction, while others are known determinants of pathogenicity and host specificity such as the viral polymerase PB2 E627K substitution. These observations suggest that enhanced growth characteristics and modified cell tropism may contribute to increased virulence in mice. We conclude that multiple amino acid substitutions are likely to be involved in the adaptation of H9N2 avian influenza virus to mice.     

鸡的钙磷营养与科学利用

在现代养鸡生产中,钙磷饲料的科学利用是保证养鸡生产成功的关键问题之一,也是饲料生产企业非常关注的问题。如何根据鸡对钙磷营养需要的原理：在生产中科学地使用钙磷饲料应该引起重视。     

饲养方式对蛋鸡产蛋前期生产性能的影响

试验通过对比舍外散放蛋鸡与舍内笼养蛋鸡在体重、胫长和胫围等方面的差异来研究饲养方式对鸡产蛋前期生产性能的影响.结果表明:散放鸡体重在8、10、12周龄显著低于同周龄笼养鸡;散放鸡胫长在10、12周龄显著低于同周龄笼养鸡;散放鸡胫围在10周龄显著低于同周龄笼养鸡.笼养鸡和散放鸡各周龄的胫长和胫围变异系数均小于10%,均匀...