Evaluation of the effectiveness of two infectious bronchitis virus vaccine programs for preventing disease caused by a California IBV field isolate

Infectious bronchitis virus CA99 serotype was isolated from several broiler flocks in Northern California. The virus caused late-onset respiratory disease and increased airsacculitis condemnation in affected flocks despite the use of an established infectious bronchitis virus vaccination program. An experimental study compared Holland/Arkansas and Massachusetts/Arkansas vaccination protocols to determine the efficacy of commercial infectious bronchitis virus vaccines in reducing respiratory disease and airsacculitis lesions found at processing that were associated with a CA99 field isolate. All vaccination groups were given Massachusetts/Connecticut strains of infectious bronchitis virus vaccines at age 1 day followed by vaccination with either Holland/ Arkansas or Massachusetts/Arkansas vaccine strains at 18 days of age. Birds were challenged at age 31 days with a CA99 field isolate. Gross pathology, histopathology, and virus isolation were evaluated. Chickens vaccinated with Holland/Arkansas had marginally better protection against CA99 challenge than chickens vaccinated with Massachusetts/Arkansas, although differences were not statistically significant.     

Molecular and serologic characterization, pathogenicity, and protection studies with infectious bronchitis virus field isolates from California

In this study, we characterized three variant infectious bronchitis virus (IBV) strains isolated in 2003 and 2004 from broiler chickens in California and compared them to previously isolated California variant viruses and to common vaccine serotypes used in the United States. We conducted genetic, serologic, and pathogenicity studies on all three isolates, then tested different vaccines against one of the viruses. Genetically the three variant IBV strains, designated CA557/03, CA706/03, and CA1737/04, were not related to each other. GenBank BLAST database search and phylogenetic analysis of the hypervariable region of the S1 subunit of the spike gene to determine the most closely related viruses to the three variants showed the CA557/03 variant to be 81.8% similar to the CAV/CA56b/91 whereas the CA706/03 and CA1737/04 variant viruses were only distantly related to Dutch/D1466/81 (72.2%), a vaccine strain used in Europe, and Korea/K142/02 (72.7%), a Korean field isolate, respectively. Cross virus-neutralization testing showed that none of the 2003-04 California IBV variant viruses were serologically related to each other or to Ark, Conn, or Mass vaccine strains. In addition the CA1737/04 isolate was also tested against DE072 and found not to be serologically related. All three variant viruses were pathogenic in 1-wk-old broilers and vaccination with Mass/Conn followed by Holland/Conn provided 80% protection against the CA1737/04 virus. The 2003-04 California variant viruses were not compared with variants isolated in California during 1970s and 1980s because, to our knowledge, no genetic information is available and those viruses are no longer obtainable. This study shows that the CA557/03 virus was distantly related to the CAV-type viruses isolated in California in the early 1990s, but that none of the 2003-04 viruses were similar genetically or serologically to the CAL99-type viruses, indicating that new IBV variants continue to emerge and cause disease in commercial chickens in California.     

西藏地区青稞籽粒营养品质分析及评价

为探明西藏地区青稞品种间的性状差异及性状间的相关性,筛选优异品质青稞种质,以251个西藏青稞种质资源为材料,测定了籽粒淀粉、粗蛋白、β-葡聚糖、γ-氨基丁酸、大量元素（Ca、P）、微量元素（Fe、Zn、Se）含量共9个品质指标,分析了被测指标间关系。结果表明,所测定的9项品质指标在供试种质资源间均存在不同程度的差异,淀粉含量的变异系数最小,Se含量的变异系数最大;粗蛋白与淀粉含量呈极显著负相关（r= -0.54）,粗蛋白与γ-氨基丁酸、Ca、P、Zn、Fe含量均呈极显著正相关。对被测指标进行主成分分析发现,可将9项品质指标简化成3个主成分,其累积方差贡献率为74.5%,其中第一主成分因子的贡献率达到了 48.0%,第一主成分中因子载荷量大的品质指标是Zn、P、Ca、粗蛋白、γ-氨基丁酸、淀粉、Fe含量。综合评价筛选出10个营养品质较高的种质,分别为BJX152、BJX008、BJX149、BJX004、BJX003、BJX015、BJX005、藏青2000、BJX227、喜马拉22号。     

土壤质量生物学指标研究进展

本文对近年土壤微生物、土壤酶活性和土壤动物等土壤质量生物学指标研究成果进行了综合评述。土壤微生物是土壤有机组分和生态系统中最活跃的部分,被认为是最敏感的土壤质量生物学指标:微生物生物量代表参与调控土壤中能量和养分循环及有机物质转化所对应微生物的数量,但须结合多样性研究以弥补其无法反映土壤微生物组成和区系变化的缺陷;微生物群落组成和多样性动态反映土壤中生物类群的多变性和土壤质量在微生物数量和功能上的差异;土壤微生物活性体现在土壤微生物商、微生物呼吸和代谢商等方面,应考虑生物量大小与微生物种群活性间的相关关系以反映微生物种群内的差异。土壤酶活性具有极高时效性,在较短时间内就能反映出土壤质量的变化。土壤动物通常以种类的组成和数量,土壤动物区系的相对丰度、多样性或活性作为评价土壤生物质量的敏感指标。与土壤理化指标相比,土壤生物学指标更能对土壤质量的变化做出灵敏迅速的响应,因而被广泛地用于评价土壤质量。     

臭柏的核型分析

臭柏（Ｓａｂｉｎａ ｖｕｌｇａｒｉｓ）体细胞染色体数目为２ｎ＝２２,其核型公式为２ｎ＝２ｘ＝４ｎ（ｓｃ）＋１６ｍ＋２Ｍ,按Ｓｔｅｂｂｉｎｓ的核型分类原则,臭柏的核型属１Ａ型。     

基于拉萨市农产品销售物流配送的现状及问题研究

文章从"互联网+"的角度出发,通过实地调研、走访及结合我国农产品销售配送的现有形式,系统的分析了拉萨市农产品销售和农产品物流配送的现状及存在的问题;从而构建一种高效便捷的城市农产品配送系统,其中包括农产品进入市场的初始环节、交易环节、仓储配送环节以及存取物环节.     

农业面源污染影响因子及控制技术的研究现状与展望

面源污染的严重性受到国内外普遍关注,并已成为国际水环境问题研究的活跃领域。本文在简要介绍农业面源污染发生机理和特征的基础上,首先综述了土地利用方式、农田耕作、田间水肥管理、地形地貌、气候水文特征和社会经济因素等农业面源污染影响因子的研究现状,然后从人工湿地技术、前置库技术、缓冲带技术、水土保持技术、农田养分管理技术和农业生态工程技术等几个方面阐述了近年来国内外农业面源污染控制技术的最新研究进展,并结合我国实际提出今后农业面源污染的研究重点。     

耕作制度对紫色水稻土根际与非根际土壤有机碳矿化的影响

以稻田免耕长期定位试验点为平台,研究耕作制度对紫色水稻土根际与非根际土壤有机碳矿化的影响。结果表明,不同耕作制度下稻田土壤有机碳日均矿化量均表现前期快速下降而后逐渐趋于平稳,培养结束时有机碳日均矿化量仅为第1天的3.1%～6.7%;另外,实行稻油轮作可有效降低土壤有机碳矿化速率。垄作免耕(中稻-油菜)处理有机碳日均矿化量、累积矿化量及矿化强度均为根际大于非根际土壤,而其他处理则是根际小于非根际土壤。稻田根际与非根际土壤有机碳平均日均矿化量随培养时间均符合幂函数变化规律,在62d培养期内,除第1天外,非根际土壤平均日均矿化量均大于根际土壤平均日均矿化量,差异变幅范围为67.0%～98.7%。各处理稻田根际与非根际土壤有机碳日均矿化量、累积矿化量和矿化强度均与其相应pH显著相关;根际与非根际土壤间有机碳日均矿化量和累积矿化量差异均与其微生物生物量碳、氮含量显著相关。