有限元法在打结器钳嘴应力分析中的应用

将钳嘴PROE模型无缝导入ANSYS软件中,利用有限元方法对钳嘴易产生应力集中的部位进行了分析.通过计算得到了钳嘴的结构应力分布规律和变形量;通过对危险截面的强度校核验证了原设计方案的可靠性,从而为该钳嘴优化设计方案的最终确定提供了理论依据,同时也为轴类结构设计提供了一种有效的方法.     

实用饲粮锰缺乏对肉仔鸡组织含锰超氧化歧化酶活性及其线粒体超微结构的影响

用1日龄Arbir Acres雏鸡64只(1/2,1/2♀),分成2组,分别喂以含锰(Mn)17ppm的缺Mn玉米-豆饼基础饲粮和含Mn137ppm的补Mn(试剂级MnSO_4·H_2O)饲粮28天。结果表明,实用饲粮Mn缺乏促使肝和心的Mn含量降低(P<0.01),心脏含Mn超氧化歧化酶(MnSOD)活性降低约26％(P<0.01),而对肝MnSOD无影响(P>0.05)。Nn缺乏导致心和肝线粒体超微结构异常,包括心线粒体萎缩退化、“分裂”趋势、肝线粒体的“融合”趋势、心肝线粒体的脊排列不规则和有的外膜丢失,且心和肝粗面内质网均明显扩张。Mn缺乏使鸡腿病发生率增加,血浆谷草转氨酶(GOT)、谷丙转氨酶(GPT)活性和尿酸含量升高(P<0.01),肌酸磷酸激酶(CPK)活性虽有增加趋势,但不显著(P<0.05)。鸡的生长性能无显著变化(P>0.05)。     

实用饲粮锰缺乏对肉用仔鸡骨骼发育的影响

用一日龄Arbor Acres肉用仔鸡64只,公母各半,分成两组,分别喂给含锰17mg/kg的玉米一豆饼型基础饲粮和含锰137mg/kg的补锰饲粮28天。基础饲粮中锰的缺乏明显地增加鸡的腿病发生率(90.6％对15.6％);降低了跖骨的长/宽比值及跖骨灰中锰浓度(P<0.01);引起跗关节肿大,肌腱从踝部滑落,长骨弯曲短粗,骺软骨骺板缩短,细胞间的基质减少,细胞紧集一起,排列无序且变形。但对骨钙化和骨灰中钙、磷、镁、铜、铁、及锌的含量则无明显影响(P>0.05)。     

中脚趾骨灰锰含量作为肉仔鸡锰生物学有效性评价指标的可行性研究

用一日龄Arbor Acres(AA)雏鸡80只(公母各半)进行试验,研究中脚趾骨灰Mn含量替代跖骨灰Mn含量作为肉仔鸡Mn生物学有效性评价指标的可行性。玉米一豆饼基础饲粮(含Mn 22ppm)分别添加无机Mn(试剂级MnSO_4·H_2O)0、50、100、150和200ppm,自由采食28天。随饲粮Mn的增加,中脚趾骨灰及跖骨灰中的Mn含量均高度线性上升(P<0.01),它们之间以及它们与饲粮Mn添加水平间的相关系数分别达0.9963、0.9713和0.9870,差异极显著(P<0.01)。结果提示,中脚趾骨灰Mn含量可满意地代替跖骨灰Mn含量而用于评价肉仔鸡Mn的生物学有效性。     

Improvement of foreign gene expression in transgenic rice ( Oryza sativa L. ) by matrix attachment regions (MARs)

Matrix attachment regions or matrix associated regions (MARs) were special DNA sequences in chromatin of eukaryotic cells that tightly associated with the nuclear matrix or scaffold in vitro after a combination of nuclease digestion and extraction. They were also called scaffold attachment regions (SARs).     

实用饲粮中锰的添加水平对肉用仔鸡组织中其他矿物元素浓度的影响

用一日龄 Arbor Acres 肉用仔鸡(公母各半)进行两个饲养试验,测定不同无机锰添加水平对肉用仔鸡肝、胰、肾、心、脾、肌肉和骨中钙、磷、镁、铜、铁和锌浓度的影响。试验1的玉米—豆饼基础饲粮含锰18毫克/千克,分别添加锰0、32、72、112、262和2822毫克/千克;试验2的相同基础饲粮含锰16毫克/千克,分别添加锰0、20、40、60、80、100、120和140毫克/千克。笼养28天。结果表明,在实用基础饲粮中添加20—262毫克/千克锰时,可提高胰和肾锌(P<0.05或0.01)及肝铜(P>0.05)的浓度,但不同添加水平间无明显差异(P>0.05)。添加水平达2822毫克/千克,增加肝铜(P<0.01)而降低骨灰镁浓度(P<0.05或0.01)。组织钙、磷、和铁的浓度无明显变化(P>0.05)。     

Antibiotic treatment of experimentally Borrelia burgdorferi-infected ponies

The objective of this study is to determine whether doxycycline, ceftiofur or tetracycline could be effectively used to treat equine Lyme disease. Ponies experimentally infected with Borrelia burgdorferi by tick exposure were treated with doxycycline, ceftiofur or tetracycline for 4 weeks (28 days). Doxycyline and ceftiofur treatment were inconsistent in eliminating persistent infection in this experimental model. However, tetracycline treatment seems to eliminate persistent infection. Although serum antibody levels to B. burgdorferi in all ponies declined gradually after antibiotic treatment, three out of four ponies treated with doxycline and two out of four ponies treated with ceftiofur, serum KELA titers were raised again 3 month after treatment was discontinued. Five months after antibiotic treatment, tissues aseptically collected at necropsy from ponies with increased antibody levels after antibiotic treatment also showed culture positive to B. burgdorferi in various post-mortem tissues. However, all four-tetracycline treatment ponies showed a negative antibody level and culture negative from post-mortem tissues. Untreated infected ponies maintained high KELA titers throughout the study and were tissue culture positive.     

Investigation on the Production Performance of gE Antibody Positive Sows in Pig Farms Infected with Wild Type Pseudorabies Virus

Pseudorabies (PR) is caused by the Pseudorabies virus (PRV). It is an acute and hot highly contagious disease infecting livestock and a wide range of wild animals. In order to investigate the relationship between latent infection of Pseudorabies virus and sow production performance,this study collected production parameters of first-parity sows with wild virus gE positive and negtive in a Pseudorabies positive stable intensive farm, including total litter size, healthy litter size, weak litter size, stillbirths, mummified fetus, litter weight, number of weaning live, number of weaning qualified and weaning weight. And compared the production performance of PRV gE antibody negative and positive sows in the same intensive pig farm. The study showed that each PRV gE antibody negative sow could produce 11.96 live piglets per parity. Additionally, PRV gE antibody negative sow could provide more alive, weaning and weaning qualified piglets per parity than infection sows, which were 0.63, 0.18 and 0.28, respectively. Although the average birth weight and average weaning weight of piglets produced by PRV gE antibody positive sows were higher than those produced by negative sows, the weaning qualified rate of antibody negative sows was higher than that of antibody positive sows, indicating that the weaning live piglets produced by antibody negative sows had higher uniformity. In summary, the production performance of PRV gE antibody positive sows was lower than that of the negative sows. Eradication of PR can bring higher profit to the pig farm. Pig farm should actively eradicate the PR.     

猪繁殖与呼吸综合征病毒(PRRSV)协同感染细菌性疾病的分析研究

为了解湖北某养殖场猪繁殖与呼吸综合征病毒（porcine reproductive and respiratory syndrome virus,PRRSV）流行毒株的遗传变异和临床感染情况,试验采集10份疑似PRRS发病仔猪的肺脏、淋巴结等临床样品,应用RT-PCR方法扩增PRRSV的Nsp2部分基因用于定性检测分析,并对扩增的其中2份PRRSV阳性样品进行ORF5基因核苷酸序列测定,结合不同疫苗毒株开展同源性比对分析。为进一步揭示病因,通过多重PCR方法对10份发病猪的肺脏和12份鼻拭子样品进行了相关致病菌的鉴定,并对其中的2株不同病原菌开展药敏试验。结果显示,10份临床样品中有5份检测到美洲型变异PRRSV,病原阳性率为50%。ORF5全基因序列分析表明,2个流行毒株间的核苷酸同源性为99.7%,与以TJM-F92、JXA1-R、HuN4-F112等为代表的高致病性致弱疫苗毒株核苷酸同源性最高,为96.7%~97.0%;与美洲型标准毒株VR2332的同源性分别为87.6%和87.9%;与国内较早分离的经典毒株（CH-1R和R98株）的核苷酸同源性分别为92.9%和87.4%、87.7%。患病猪临床常见感染模式为PRRSV+PM+SS、PRRSV+PM或PRRSV+HPS,2株主要致病菌药敏试验表明,多杀性巴氏杆菌对头孢曲松、阿莫西林等药物高度敏感,猪链球菌对阿莫西林、氨苄西林、阿奇霉素等药物高度敏感。本研究揭示了该场保育猪的发病病原,并从分子水平明确了临床PRRSV与不同疫苗毒株的亲缘关系,为弱毒疫苗的合理选择使用和综合防控PRRS提供了实践依据。