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。     

番茄品种耐弱光性的综合评价

研究了苗期弱光条件对幼苗素质，开花，果实大小及产量的影响，采用模糊数学的隶属法对品种的耐弱光性进行评价，并探讨了番茄耐弱光性状的鉴定方法，结果表明，苗期弱光对幼苗素质影响最大，其次影响开花，果实大小和产量，春雷２号和春雷１号属于耐弱光惭弱的品种，白果强丰属不耐弱光品种。     

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.     

日粮添加过瘤胃保护胆碱对喀斯特山区奶牛泌乳性能的影响及其延续效应研究

研究日粮添加过瘤胃胆碱(RPC)对喀斯特山区奶牛泌乳性能及其延续效应的影响。以10头喀斯特山区泌乳盛期奶牛为试验动物,进行自身对照试验设计。试验按照对照期、正试期(试验Ⅰ期、试验Ⅱ期)、延续效应期(试验Ⅲ期)连续进行,每期12 d。其中,正试期RPC每头奶牛的添加水平为40 g/d;试验Ⅲ期停喂RPC以观察其是否可对奶产量产生延续效应。结果表明,对照期、试验Ⅰ期、试验Ⅱ期、试验Ⅲ期奶牛干物质采食量差异不显著(P>0.05)。试验Ⅰ期奶产量显著高于其他3期(25.5∶27.7∶26.5∶24.8 kg/d,P<0.05);正试期(试验Ⅰ期、试验Ⅱ期)奶产量显著高于对照期、延续效应期(25.5∶27.2∶24.8 kg/d,P<0.05);当停喂RPC后,延续效应期奶产量即下降至对照期水平(25.5∶24.8 kg/d,P>0.05)。奶成分不受日粮添加RPC的影响(P>0.05),乳脂、乳固型物含量数值上较对照期有所增加。由此可见,日粮添加RPC有利于提高喀斯特山区奶牛泌乳性能,但未对奶产量表现出延续效应,生产实践中需持续添加。     

非淀粉多糖复合酶制剂对断奶仔猪血液指标的影响

选用120头平均体重为(8.1±0.2)kg的PIC断奶仔猪,采用单因素完全随机化试验设计,研究在饲料中添加复合酶对断奶仔猪血液指标的影响。试验共设5个处理组,每个处理4个重复,每个重复6头猪。试验期为28 d,分为前期(1～14 d)和后期(15～28 d)两个阶段。结果表明:非淀粉多糖复合酶组能显著提高断奶仔猪前期血糖、总蛋白的含量(P<0.05);提高后期断奶仔猪血糖、总蛋白和免疫球蛋白A的含量(P<0.05),复合酶Ⅱ效果好于复合酶Ⅰ。     

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。     

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.     

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.     

肉种鸡群晚开产的原因分析与启示

某种鸡场于2008年5月中旬引种AA+父母代肉种鸡12 600套,至29周才见蛋,且产蛋增幅缓慢,至34周产蛋率还不足30%,与相似文献