退化草地土壤生化活性研究

通过对三种不同退化程度的退化草地土壤生化活性进行测定和相关性分析，结果表明草地退化后其土壤生化活性受到不同程度的影响，表现为土壤生化活性随着退化程度增高而减小，但差异并非都达到统计学上的显著性，而土壤生化活性间的相关性则显著地与草地退化程度有关，说明退化草地土壤微生物间的协调作用受到显著影响，从而影响土壤氮素和碳素代谢途径。     

Characterization of porcine circovirus type 2 (PCV2) infection in swine lymphocytes using mitogen-stimulated peripheral blood lymphocytes from healthy PCV2-carrier pigs

Information regarding the susceptibility of swine lymphocytes to PCV2 is rather limited. To further explore and characterize the PCV2 infection in swine lymphocytes, an in vitro model using concanavalin A (Con A)-stimulated peripheral blood lymphocytes (PBLs) obtained from clinically healthy PCV2-carrier pigs was introduced. It was found that the PCV2 antigen-containing rate was below 2% in PBLs from healthy PCV2-free pigs following treated simultaneously with Con A and PCV2. However, significantly higher PCV2 antigen- and nucleic acid-containing rates could be seen in Con A-stimulated PBLs from clinically healthy PCV2-carrier pigs. Prior to Con A treatment, both of the PCV2 antigen- and nucleic acid-containing rates in PBLs from healthy PCV2-carrier pigs were less than 1%; however, they reached 22.1+/-5.7% by flow cytometry and 27.1+/-6.5% by in situ hybridization, respectively, at 4-day post-incubation with Con A. Phenotyping of PCV2 antigen-containing cells revealed that PCV2-positive cells could be detected in both T and B lymphocyte populations within which IgM-positive B lymphocytes appeared to have a relatively higher positive rate. The Con A-stimulated PBLs also displayed a significantly higher viral load by the measurement of either PCV2 DNA copy number or viral titer when compared with the non-treated PBLs from healthy PCV2-carrier pigs. The results indicate that PBLs, especially IgM-bearing B lymphocytes, are indeed susceptible to PCV2 infection and PCV2 is capable of replicating in dividing lymphocytes. This activation-induced replication may explain in part the pathogenesis of lymphoid depletion in PMWS-affected pigs.     

奶牛真胃变位发病规律的研究

为了阐明奶牛真胃变位的发病规律，对263例奶牛患有真胃变位的自然病例进行了研究。结果表明：真胃变位的发生与过食精料和高产奶牛有密切关系，2－4胎次体格健壮的、产后30天内的、11月份到来年的5月份奶牛发病率高。     

传染性法氏囊病病毒（IBDV）人工感染SPF鸡的病理学观察

取３２０只３０～４０Ｈ龄ＳＰＦ鸡，经滴鼻和点眼接种传染性法氏囊病病毒（ＩＢＤＶ），接种后２４～７２ｈ出现死亡，病死率５１．２５％，死亡鸡剖检变化主要为法氏囊肿胀、出血，甚至呈紫葡萄样，脾脏肿大、出血，骨骼肌出血，腺胃肌胃交界处出血。病理组织学变化，呈现以法氏囊淋巴滤泡内髓质淋巴细胞坏死为主的特征性病变，并可在巨噬细胞浆内发现病毒包涵体。电镜观察，在法氏囊内淋巴细胞、异染性细胞、巨噬细胞浆内，见大量晶格状排列的病毒粒子和包涵体，表明ＩＢＤＶ首先损害法氏囊淋巴滤泡髓质内未成熟的Ｂ淋巴细胞，病毒在淋巴细胞内以包涵体方式增殖。     

应用套入式聚合酶链反应(Nested-PCR)检测蓝舌病病毒的研究

本实验建立了一种Ｎｅｓｔｅｄ－ＰＣＲ方法。应用方法检测５株标准株蓝舌病病毒（Ｔ４、Ｔ１０、Ｔ１１、Ｔ１６、Ｔ２０）和５株国内蓝舌病病毒分离株（ＣＦ４、ＡＦ６、Ｚ１、Ｈ１、Ｇ１４）,检测结果均为阳性,而检测相关环状病毒（ＥＨＤ２、ＥＨＤ６、Ｉｂｒａｋｉ）,检测结果均生。研究证明,此方法可检测到３．５ｆｇ的ＢＴＶ－ＲＮＡ,灵敏度较高。该方法成功区分了蓝病病毒和相关环状病毒,比血清学方法更加优势,在临床     

北方塑料暖棚牛舍的设计

本文采用冬季太阳高度角最小,夏季太阳高度角最大,太阳高度角随纬度变化而变化这一原理,确定牛舍棚面闻的计算公式为C=B-h(B：为50“临界值,h为太阳高度角),在舍外温度连-20℃～-30℃时夜间舍内温度达7℃～8℃以上。     

乳清酒发酵剂的优选

以2株乳酵母菌、地方性奶酒酵母泥、乳酸菌、丹宝利活性酿酒干酵母为发酵菌种,研究其在乳清酒发酵中各发酵剂的发酵能力、发酵特性并对发酵所得乳清酒品质进行了分析,筛选出5#组合菌种(乳酵母菌2,丹宝利活性酿酒千酵母、保加利亚乳杆菌和嗜热链球菌比例为10:0.1:1)为本研究最佳试验用发酵菌种.