遗传算法优化超声辅助低共熔溶剂提取红枣总黄酮工艺研究

本文采用一种新型绿色溶剂提取红枣总黄酮,并对其提取工艺进行优化.通过单因素试验探究含水量、超声功率、提取时间、提取温度和料液比对红枣总黄酮得率的影响.在此基础上,采用遗传算法优化超声辅助低共熔溶剂提取红枣总黄酮工艺.结果表明:超声辅助低共熔溶剂提取红枣总黄酮最优的工艺参数为:含水量37％、超声功率167 W、提取时间3...     

基于案例的国内动物疫病风险评估技术发展现状研究

为了解我国动物疫病风险评估研究进展,本研究对我国2006—2016年间发表的动物疫病风险评估模型相关文献进行分析。采用文献回顾的方式,就动物疫病风险评估模型的构建目标、构建方法、评估对象、模型结构及实际应用进行研究。研究表明,我国动物疫病风险评估模型研究与国际基本同步,但也存在理论体系研究薄弱、理论联系实际不足等问题。同时,提出了完善理论体系建设、推广模型应用等建议。     

一起未经执业兽医注册从事诊疗活动案引发的思考

2017年成都市办理的一起未经兽医执业注册而进行犬只声带切除的行政处罚案件,引发了笔者对动物诊疗机构监督执法中"动物诊疗"范畴界定、动物诊疗许可证申请对象探究、"一事不再罚"原则的适用、"责令停业诊疗活动"与"责令停产停业"区别等问题的思考。本文以法学理论和相关法律规定为基础,对成都市动物诊疗机构执法实践的疑点与难点进行分析,提出执法人员应更准确适用法律法规,并呼吁尽快建立全国执业兽医查询系统的建议。     

基因芯片检测细菌耐药基因

根据已知的耐药基因序列设计出检测四环素耐药基因特异探针7条、β-内酰胺类耐药基因特异探针5条,阳性坐标探针1条,长度为18-21 bp.根据探针序列两侧的保守区域设计了耐药基因扩增引物,引物长度17-20bp.通过荧光聚合酶链式反应,从耐药菌株中获得四环素耐药基因7个,β-内酰胺类耐药基因5个.经过芯片制作过程优化试验和芯片杂交优化试验,结果表明,将探针以终浓度30 μmol/L溶于50%DMSO中,在温度为20 C、湿度为70%的条件下点印于Aldehydeslide表面.扩增出的荧光标记产物经纯化后与2×杂交液混合,再与基因芯片在42 C杂交5 h可检测到理想的杂交信号.芯片灵敏度试验结果表明,当模板拷贝数大于1×103个/μL时,可检测到较强的杂交信号.本试验最终研制出灵敏度高、特异性强的耐药基因检测芯片.     

IBV AH1-99分离株N基因的克隆及序列分析

利用RT-PCR技术成功扩增出IBV AH1-99分离株的N基因全长cNDA,将其克隆到pMD18-T载体上。经酶切分析、PCR鉴定及核苷酸序列测定,成功获得该分离株N基因的重组质粒。序列分析结果表明,分离株N基因全长1 230个核苷酸,编码409个氨基酸。同部分IBV参考毒株相比,核苷酸同源性为85.8%~89.9%,氨基酸同源性为86.6%~91.0%,在进化关系树中,AH1-99与国内分离株X、LX4亲缘关系较近。     

复州牛改良情况调查研究

本研究调查了大连安波、庄河和四平镇的复州牛改良情况,通过测量体尺、评价体况,并利用肉用指数(Beef Perfomance Index,BPI)研究了牛群的经济类型。结果显示,489头改良成年母牛平均BPI为3.40~3.61,主要经济类型为肉役兼用型;23头复州成年母牛平均BPI为3.28,属役用型。改良牛群在体重、体尺生产性能指标等方面都比复州牛有了明显改善和提高。     

武汉市规模猪场粪水资源化利用典型模式探析

为有效控制规模猪场生产中产生的粪水对环境的影响,加快推进规模猪场粪水资源化利用,促进一、二、三产业融合,文章立足于武汉市规模猪场粪水资源化利用实际,选取规模猪场粪水资源化利用典型模式进行分析,以期为提高规模猪场粪水资源化利用提供借鉴.     

Feeding different dietary protein to energy ratios to Holstein heifers: effects on growth performance,blood metabolites and rumen fermentation parameters

Eighteen Chinese Holstein heifers average age 230 ± 14 days were allocated to 1 of 3 dietary crude protein (CP) to metabolizable energy (ME) ratios to examine the effects on growth performance, blood metabolites and rumen fermentation parameters with 90‐days experiment. Three different dietary CP:ME ratios were targeted based on the formulation of dietary CP contents of 10.85%, 12.78% and 14.63% on dry matter (DM) basis with similar ME contents (10.42 MJ/kg DM), which were categorized as low, medium and high dietary CP:ME ratios. The actual CP:ME ratios obtained in this study significantly increased from low to high CP:ME ratio groups with a value of 10.59, 11.83 and 13.38 g/MJ respectively. Elevated CP:ME ratios significantly increased CP intake (kg/day) and feed efficiency (FE) which was defined as dry matter intake as a proportion of average daily gain (ADG), whereas little difference was observed in body weight (kg), ADG (kg/day), DM intake (kg/day) and ME intake (MJ/day) among the three different CP:ME ratio groups. Increasing dietary CP to ME ratios significantly increased CP digestibility, whereas digestibility of DM and gross energy remained constant in the current experiment. Blood urea nitrogen and insulin‐like growth factor‐1 linearly increased with increasing dietary CP:ME ratios. There was significantly dietary treatment effect on rumen fermentation parameters including acetate, propionate, butyrate and total volatile fatty acids. Therefore, this study indicated that increasing dietary CP levels with similar energy content contributed to increased protein intake and its digestibility, as well as FE. Holstein heifers between 200 and 341 kg subjected to 13.38 dietary CP:ME ratio showed improved feed efficiency, nutrient digestibility, some blood metabolites and rumen fermentation characteristics for 0.90 kg/day rate of gain.     

猪繁殖与呼吸综合征病毒NSP2抗原表位区的原核表达及免疫原性分析

试验旨在表达纯化猪繁殖与呼吸综合征病毒NSP2重组蛋白。利用PCR技术扩增获得大小为750 bp的NSP2 226－475位氨基酸编码序列,然后将该序列亚克隆到pET-28a（+）表达载体上,通过pET-28a（+）表达载体在大肠杆菌Rosetta-gami 2（DE3）pLys中得以表达,获得大小为29 ku的重组蛋白,对重组蛋白诱导时间进行优化,SDS-PAGE显示重组蛋白在37 ℃经1 mmol/L IPTG诱导8 h时表达量最大,免疫印迹结果证实表达的蛋白能被PRRSV阳性血清识别,具有良好的免疫原性。本研究成功表达纯化了NSP2重组蛋白,为目标蛋白作为包被抗原建立检测PRRSV血清抗体的ELISA方法奠定了基础。