米易县核桃产业发展的思考

在论述了米易县核桃产业发展现状的基础上,分析了米易县发展核桃产业的必要性和存在的问题,针时存在问题提出了相应的对策和建议：一是以核桃基地建设为重点,合理规划核桃种植;二是以科技为依托,强化技术支撑体系;三是引进龙头企业,带动核桃产、工、销一体化发展;四是拓宽核桃产业发展的融资渠道;五是建立苗圃基地,确保良种供应;六是制定一系列的优惠政策,促进核桃产业健康快速发展。     

Prevalences of resistance to seven antimicrobials among fecal Escherichia coli of swine on thirty-four farrow-to-finish farms in Ontario, Canada

Fecal specimens were composited and a hydrophobic-grid membrane-filter method was used to measure antimicrobial resistance to ampicillin 16 μg/ml, carbadox 30 μg/ml, gentamicin 4 μ/ml, nitrofurantoin 32 μg/ml, spectinomycin 16 μg/ml, sulfisoxazole 32 μg/ml and tetracycline 8 μg/ml among 8119 Escherichia coli isolates from 68 fecal samples collected on 34 farrow-to-finish swine farms marketing over 500 hogs/yr. The overall prevalences of resistance to antimicrobials among these isolates were: ampicillin 29%, carbadox 3.5%, gentamicin 0.6%, nitrofurantoin 27%, spectinomycin 28%, sulfasoxizole 38% and tetracycline 71%. Thirty to seventy-six per cent of the variations in prevalences were explained by between-farm differences.     

家禽生长促进剂天然替代物

<正>自欧洲禁用抗生素生长促进剂(AGPs)以来,市场上出现了各种各样的AGPs替代品。这些产品的目的必须确保其效果至少不低于所替代的产品,而且还必须使动物的生理状态与环境相协调。     

水泡性口炎病毒核蛋白基因在大肠杆菌中的表达和鉴定

根据已经发表的IN型水泡性口炎病毒(VSV)核蛋白(N)基因的序列设计1对特异引物,应用RT-PCR技术扩增编码IN VSV的N基因,将PCR产物按相应的阅读框架克隆到表达载体pET-32a。并将重组质粒转化入大肠杆菌 BL21株,以1．0 mmol·L-1 IPTG在37℃的条件下诱导,N基因得到了高效表达。经过聚丙烯酰胺凝胶电泳以及用 VSV阳性血清进行Western blotting试验,结果表明所表达的融合蛋白产物分子质量与预期的65．3 ku相符。     

Comparison of antimicrobial resistance in generic Escherichia coli and Salmonella spp. cultured from identical fecal samples in finishing swine

The objectives of this study were to investigate the associations between antimicrobial resistance patterns in generic Escherichia coli and Salmonella spp. isolates recovered from identical pen pooled fecal samples, and to evaluate potential clustering of multiple isolates of these organisms within identical fecal samples. Up to 5 generic E. coli (n = 922 isolates) and Salmonella spp. (n = 922 isolates) isolates were obtained from each of 188 pen pooled fecal samples that had been collected from 45 finishing swine farms in Alberta in 2000, and tested for susceptibility to 15 antimicrobials. No isolates of either organism were resistant to 3rd generation cephalosporins or fluoroquinolones, which in Canada are considered antimicrobials of very high importance to human health. Approximately twice as many generic E. coli isolates as Salmonella spp. isolates were resistant to at least 1 antimicrobial. In addition, E. coli isolates showed more multidrug-resistance patterns. No significant association was observed between the resistance phenotypes of Salmonella spp. and E. coli at the fecal sample level. More clustering at the sample level was observed for proportions of antimicrobial resistance (AMR) in Salmonella spp. isolates than E. coli indicating that in future studies it might be sufficient to test fewer than 5 Salmonella spp. isolates per sample.     

A temporal study of Salmonella serovars from environmental samples from poultry breeder flocks in Ontario between 1998 and 2008

A temporal study was carried out to determine Salmonella prevalence, trends, major serovars, and their clusters from environmental samples, in poultry breeder flocks in Ontario between January 1998 and December 2008. Surveillance data were obtained from the Ontario Hatchery and Supply Flock Policy. Logistic regression with a random effect for flock was used to identify factors [poultry type, year (trend) and season] associated with the prevalence of Salmonella. A cluster detection test was used to identify clusters of common serovars. The period prevalence of Salmonella was 47.4% in broiler-breeder, 25.7% in layer-breeder, and 19.6% in turkey-breeder flocks. The overall trend in the prevalence of Salmonella was decreasing for all breeder types, due primarily to decreasing trends of Salmonella Heidelberg. The seasonal effects varied by year with the highest probability of Salmonella occurring in different seasons. The 4 most common serovars identified were Salmonella Heidelberg, Kentucky, Hadar, and Typhimurium in broiler-breeders; Salmonella Heidelberg, Brandenburg, Thompson, and Typhimurium in layer-breeders; and Salmonella Heidelberg, Saintpaul, Brandenburg, and Muenster in turkey-breeders. Salmonella Enteritidis was infrequently isolated in all poultry breeder types. Temporal clusters of different serovars were identified in all poultry breeder types. Clusters of Salmonella Heidelberg, Typhimurium, and Hadar from environmental samples from breeder flocks were detected during a similar period to clusters from hatchery fluff samples from the same population. Therefore, interventions at the breeder flock-level might help to reduce transmission of Salmonella from breeder flocks to hatcheries and possibly, to lower levels of the poultry production chain.     

中国施用生物炭对番茄产量和品质效应的Meta分析

为定量分析生物炭施用对番茄产量和品质的时空效应和影响机制,同时为番茄生产中生物炭合理施用量的确定提供依据。该研究通过检索文献整合已发表的相关田间试验数据,采用Meta-analysis法分析了生物炭施用条件下,生物炭特性、土壤条件、田间管理措施与时空特性对番茄产量和品质的综合效应,并对各影响因素进行通径分析。结果表明：施用生物炭显著增加了番茄产量、果实Vc、可溶性糖和可溶性固形物含量（P<0.05）,增长率分别为 30.7%（95%置信区间（confidence interval,CI） 为27.6%～33.9%）、13.8%（95% CI为10.8%～16.9%）、6.7%（95% CI为3.3%～10.2%）和10.7%（95% CI为5.8%～15.8%）,而番茄果实硝酸盐含量降低了3.1%（95% CI为-6.7%～0.8%）,对番茄果实糖酸比含量增加效应不显著（95% CI为-3.0%～7.9%）;番茄产量效应的亚组分析表明,生物炭施用在不同时间和区域特征下对番茄增产效应影响显著（P＜0.01）,随着时间的推移,生物炭施用对番茄增产效应呈波动式增长趋势,华北、东北农田区的番茄增产效应不显著;土壤有机质含量与番茄增产率呈正相关关系,土壤pH值与番茄增产率呈负相关关系,番茄增产率随土壤全氮及硝酸钾含量的增加呈先增后减趋势;田间管理措施对番茄产量效应分析结果表明,生物炭施加量>40～80 t/hm²时,增产率可达37.8%（95% CI为33.5%～42.1%）,生物炭热解温度在400～600 ℃内,生物炭pH值控制在>8～9为最优;生物炭施用量、生物炭pH值和产量年份是影响生物炭增产效果的3个主要因素。研究结果可为番茄生产中科学、合理生物炭施用量的确定提供理论支撑。     

The application of knowledge synthesis methods in agri-food public health: Recent advancements,challenges and opportunities

Knowledge synthesis refers to the integration of findings from individual research studies on a given topic or question into the global knowledge base. The application of knowledge synthesis methods, particularly systematic reviews and meta-analysis, has increased considerably in the agri-food public health sector over the past decade and this trend is expected to continue. The objectives of our review were: (1) to describe the most promising knowledge synthesis methods and their applicability in agri-food public health, and (2) to summarize the recent advancements, challenges, and opportunities in the use of systematic review and meta-analysis methods in this sector. We performed a structured review of knowledge synthesis literature from various disciplines to address the first objective, and used comprehensive insights and experiences in applying these methods in the agri-food public health sector to inform the second objective. We describe five knowledge synthesis methods that can be used to address various agri-food public health questions or topics under different conditions and contexts. Scoping reviews describe the main characteristics and knowledge gaps in a broad research field and can be used to evaluate opportunities for prioritizing focused questions for related systematic reviews. Structured rapid reviews are streamlined systematic reviews conducted within a short timeframe to inform urgent decision-making. Mixed-method and qualitative reviews synthesize diverse sources of contextual knowledge (e.g. socio-cognitive, economic, and feasibility considerations). Systematic reviews are a structured and transparent method used to summarize and synthesize literature on a clearly-defined question, and meta-analysis is the statistical combination of data from multiple individual studies. We briefly describe and discuss key advancements in the use of systematic reviews and meta-analysis, including: risk-of-bias assessments; an overall quality-of-evidence approach; engagement of stakeholders; Bayesian, multivariate, and network meta-analysis; and synthesis of diagnostic test accuracy studies. We also highlight several challenges and opportunities in the conduct of systematic reviews (e.g. inclusion of grey literature, minimizing language bias, and optimizing search strategies) and meta-analysis (e.g. inclusion of observational studies and approaches to address the insufficient reporting of data and significant heterogeneity). Many of these developments have yet to be comprehensively applied and evaluated in an agri-food public health context, and more research is needed in this area. There is a need to strengthen knowledge synthesis capacity and infrastructure at the regional, national, and international levels in this sector to ensure that the best available knowledge is used to inform future decision-making about agri-food public health issues.