用大肠杆菌K99和F41菌毛抗原检测牛血清抗体的琼脂扩散试验的研究

用含２ｍｏｌ／Ｌ尿素的磷酸盐缓冲液以热处理方法提取的Ｋ９９和Ｆ４１菌毛作为抗原,对琼脂扩散试验方法进行研究。结果表明本试验方法简便,特异性强,敏感性高,可用于血清抗体检测;所制备的抗原稳定、重复性好。     

小尾寒羊多胎性能候选基因的研究进展

小尾寒羊具有常年发情、性成熟早和多胎性能的高繁殖力特性,平均每胎产羔2.6只,是我国优良的地方绵羊品种,也是我国独特的遗传资源。目前在BooroolaMerino羊、Inverdale羊和Hanna羊中已找到影响多胎性能的主基因,但国内对小尾寒羊多胎性能遗传机制的研究主要集中在常规的选育和分子标记方面,也有一些以候选基因法从分子水平上对小尾寒羊多胎机制进行研究,仍没有确立控制小尾寒羊高繁特性的主效基因,本文就其研究现状进行综述,为小尾寒羊主效基因的研究提供有益的参考。     

不同密度的羊草种群结构及其光照分布的研究

本文报道了耕翻后自然更新的羊草种群不同密度条件下垂直结构及其光照分布特征。结果表明,地上生物量和叶面积指数均以种群中部最大,向上或向下皆逐渐减小。在三种密度中,生物量,叶面积指数,株高,茎高和叶片含水量均随着密度的增大而升高。比叶重和单株绿叶数度增加而降低。     

参加央视《中国工作犬大集合》节目后两警犬再立新功

参加完中央电视台《中国工作犬大集合》节目后的工作犬,他们回到各自的岗位上,有什么突出表现呢?     

浅谈油气管道完整性管理模式

本文基于国内外油气管道完整性管理(PIM)成果的基础,从数据收集和研究、高后果区分析、完整性评估、管道检测与执行、管道维护修复、效能分析等方面进行具体PIM描述,从体系文件、标准规范、系统平台、支持技术、实施应用五个层面构建PIM管理体系框架。     

用PPA-ELISA测HCLV抗体和抑制法测HCLV

对早期建立的PPA-ELISA测猪瘟兔化弱毒(HCLV)抗体和PPA-ELISA抑制法测HCLV毒价的2种方法作总结性回顾。前者用于猪瘟的免疫监测,以抗体的分布曲线显示HCLV的免疫效果,出现低谷为免疫力不足,出现特异高峰则可能有强毒侵入;如群体保护率小于50%,表明免疫失败。后者主要用于细胞培养液小样的HCLV毒价测定,方法简单,一次能测多个样品。检测结果表明,在现用的疫苗中抑制价高的,完全有可能用16万或20万倍稀释通过兔体测毒。对此,建议将兔体半数反应量(RID50)标准提高至16万或20万倍稀释,一次通过,免疫剂量用400RID50,与国际接轨,达到早日消灭猪瘟的目标。     

Acaricidal activity of extracts of neem (Azadirachta indica) oil against the larvae of the rabbit mite Sarcoptes scabiei var. cuniculi in vitro

The acaricidal activity of the petroleum ether extract, the chloroform extract and the acetic ether extract of neem (Azadirachta indica) oil against Sarcoptes scabiei var. cuniculi larvae was tested in vitro. A complementary log-log (CLL) model was used to analyze the data of the toxicity tests. The results showed that at all test time points, the petroleum ether extract demonstrated the highest activity against the larvae of S. scabiei var. cuniculi, while the activities of the chloroform extract and the acetic ether extract were similar. The activities of both the petroleum ether extract and the chloroform extract against the larvae showed the relation of time and concentration dependent. The median lethal concentration (LC(50)) of the petroleum ether extract (1.3muL/mL) was about three times that of the chloroform extract (4.1muL/mL) at 24h post-treatment. At the concentrations of 500.0muL/mL, the median lethal time (LT(50)) of the petroleum ether extract and the chloroform extract was 8.4 and 9.6h, respectively.     

玉米胚芽粕对鹅营养价值的评定

为了探索玉米胚芽粕对鹅的营养价值和不同方法、不同鹅品种对其真代谢能、常规养分利用率的差异,分别选取150日龄健康五龙鹅和青农灰鹅公鹅各24只,各设4个处理组,每个处理组6只,试验鹅单笼饲养,每天强饲120 g,采用全收粪法进行测定.结果表明,五龙鹅、青农灰鹅种内4个处理组之间真代谢能(THE)、粗蛋白(CP)、粗脂肪(EE),A基酸(AA),中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、粗纤维(CF),it,(Ca),磷 (P)利用率差异均不显著(P>0.05).两品种之间,第2,4处理组青农灰鹅THE、CP真利用率显著(P<0.05)或极显著(P<0.01)高于五龙鹅;第3,4处理组青农灰鹅EE利用率显著(P<0.05)或极显著(P<0.01)高于五龙鹅.第1,3或4处理组五龙鹅NDF,CF利用率显著(P<0.05)高于青农灰鹅相应各处理组.由此可知,鹅对玉米胚芽粕的养分有较高的利用率;同品种不同处理下鹅对玉米胚芽粕的THE,常规养分利用率差异均不显著;不同品种鹅对玉米胚芽粕的养分利用率存在一定差异.     

Caspase 3 is not likely involved in the postmortem tenderization of beef muscle

Postmortem proteolysis is an important determinant of beef tenderness. Caspase 3 is a protease that functions in apoptosis and has been shown to degrade myofibrillar proteins. Our objective was to evaluate whether caspase 3 activity is related to beef tenderness and muscle growth, and whether caspase 3 is activated in postmortem beef muscle. In experiment 1, longissimus thoracis (LT) and sternomandibularis muscle samples were obtained at 0, 0.25, 1, 3, 24, 72, and 240 h postmortem from 5 steers. In experiment 2, a group of 40 beef cattle was slaughtered at the University of Wyoming Meat Lab with 10 steers of different tenderness and growth characteristics chosen for the analysis of caspase 3 activity in the LT. In experiment 3, 10 steers with different tenderness but matched growth characteristics were chosen for analyses. In experiment 1, no significant activation (P = 0.70) of caspase 3 activity was detected; only a decreased activity at 72 (P = 0.05) and 240 h (P = 0.02) postmortem was observed. Western blot analysis of both muscle samples showed only the pro-caspase 3 form and failed to detect the activated enzyme. In experiment 2, caspase 3 activity in the LT immediately postmortem was greater (P = 0.05) for the cattle with increased Warner-Bratzler shear force values. No difference in caspase 3 activity was detected for experiment 3. Our results demonstrate that caspase 3 activity is not activated, with its activity decreasing with time postmortem, and caspase 3 activity is not associated with Warner-Bratzler shear force at slaughter. Therefore, caspase 3 is not anticipated to be involved in postmortem tenderization of beef.     

低聚糖对雏鸡大肠粪便NH3-N含量及肠道菌群的影响

试验选取1日龄罗曼蛋公雏250只，随机分为5组，试验组饲料或饮水中分别添加海藻糖(500mg／kg)、海藻胶(600mg／kg)、大豆寡糖(500mg／kg)、圆葱寡糖(500mg/d)。结果表明，四种低聚糖均可促进肠道乳酸菌及双歧杆菌的生长繁殖，对魏氏梭菌的生长呈现抑制作用。海藻糖、海藻胶对降低大肠粪便NH3—N含量效果不显著(P＞0．05)，而大豆寡糖效果显著(P＜0．05)，圆葱寡糖效果极显著(P＜0.01)。