Experimental and natural infection with the enzootic leukosis virus of cattle

A trial was performed with heifers at the age of six to seven months. The animals were experimentally infected with the lymphocytes of a virus-productive donor. Infection was produced in all the nine cases, as demonstrated by means of the positive syncytial test. As indicated by the results of the trial, the antibodies to the enzootic bovine leucosis virus (BLV) were produced soon after experimental infection. A high sensitivity of the serum-neutralization test and the ELISA method was demonstrated in this connection: by these methods, the antibodies were identified already two to three weeks after experimental infection whereas by the immunodiffusion test they could be detected only after five weeks. Twenty-four animals were exposed to natural contact infection. Within 270 days of the trial, the disease after contact was recorded only in one heifer out of the four that were in close contact with the experimentally infected animals. In this case, as compared with experimental infection, the antibodies were produced much later--after 85 to 93 days. Leucosis was recorded in none of the remaining animals. The reasons why such a favourable result was obtained were the thorough disinfection of the stables after blood collections and the strict observance of the aseptic conditions. The results of experimental infection in three cows were identical with those obtained in young cattle. In the experimentally infected dairy cows, antibodies in milk were determined by the ELISA method. As found, in milk the antibodies to BLV appear two to three weeks later than they do in serum. The ELISA method of BLV antibody detection can be used for the identification of infected animals in herds where enzootic bovine leucosis occurs.     

新西兰乳业概况

1发展历史新西兰乳制品工业始于1814年,当时从国外进口了两头成母牛和一头公牛;1871年,第一个合作社性质的乳品公司成立并开始生产奶酪;1882年,第一船冷冻黄油销往英国。回首新西兰乳制品工业的历史,创新和技术是其走向成功的重要因素,早期的创新包括1884年奶油分离技术和18世纪80年代机械挤奶设备的引入。当时,追求进步的思想渗透到新西兰乳制品工业的各个环节,从农场原料奶生产、处理、深加工到市场销售。2乳业介绍新西兰虽然仅有400万人口,但乳业相当发达。奶牛总头数为530多万头(包括小牛和种用公牛),其中泌乳母牛为390万头,分布在全国1…     

污水污物潜水旋流泵性能及设计方法试验研究

对影响潜水旋流泵性能的6个主要过流件几何参数进行了试验研究，初步掌握了旋流泵叶轮及泵体主要几何尺寸对性能影响的规律。在分析16种优秀水力模型的基础上，计算出叶轮D2及b2函数回归方程式，并用设计实例进行检验，样机效率比国内外同类产品提高3％左右。     

Specificity of the carbon immunoassay (CIA) test for the diagnosis of Toxoplasma infections.

A rapid and low cost procedure, the carbon immunoassay (CIA) test, was evaluated for the diagnosis of Toxoplasma gondii infections. Using a closely related parasite (Besnoitia jellisoni) as antigen, and homologous or heterologous immune sera, it was demonstrated by light and electron microscopy that CIA is a very reliable and specific test. As it is neither expensive nor time-consuming, it can be recommended for general and routine laboratory use.     

Teratological examination of the insecticide methyl-parathion (Wofatox 50 EC) on pheasant embryos. 2. Biochemical study.

Fertile pheasant's eggs were treated with the insecticide Wofatox 50 EC (50% methyl-parathion) by injection technique on day 12 of the hatching period. Treatment consisted of inoculation of 0.1 ml of different concentrations of the insecticide into the air space of embryonated eggs. The following dose levels were employed: 0.00, 1.35, 13.5 and 135.0 mg/kg egg of active ingredient. Biochemical changes in the plasma were evaluated by micro (photometric) methods which rendered possible the determination of several blood plasma variables of the embryos. At the highest dose level applied, serum alkaline phosphatase (SAP) enzyme activity and inorganic P concentration of the treated embryos showed statistically differences (reduction) as compared to the control data. Macroscopic alterations were detected at necropsy.     

N_(98s)×特青(亚种间杂交稻)抽穗后物质生产及分配特点研究初报

对N×特青示范田中试区与肥料试验田各处理小区稻株分析结果表明:抽穗后,亚种间杂交稻N×特青比常规稻特青干物质生产能力强,灌浆速度快;地上部各器官占植株干重比例,前者叶片比重大于茎,后者茎比重大于叶。亚种间杂交稻对肥料反应敏感,抽穗后,干物质累积,植株高度,每穗总粒数和粒重均随施肥量增加而增加,在高肥区有利于进一步提高产量,但增施氮肥后,灌浆速度明显滞后。     

农业产业化主体的困惑——个人理性与团体理性的冲突

龙头企业、中介服务机构和农户构成农业产业链条不可缺少的组成部分。任何一方对个人理性的盲目追求，会损害团体理性。因此，有必要对个人理性作适当的调整，以利于团体理性的发挥。     

60日龄肉鹅发生小鹅瘟的诊治

吴川市板桥镇某养鹅专业户饲养的一群肉鹅，６０日龄时发生一种以下痢、脱水死亡为特征、伴有阵发性抽搐及扭头神经症状的疫病。经诊断检查，确诊为小鹅瘟病，现将诊治情况报告如下：１发病情况２０００年４月１９日，该专业户共购进雏鹅１８７只，１日龄时注射抗小鹅瘟血清，每只鹅１ｍＬ，育雏期间共死亡３只，尚余１８４只。养至６月１８日时发现病鹅１只，２０日病鹅发展到５只，并出现死鹅１只。至２２日时共发病１０只，死亡５只。发病期间，鹅主曾用土霉素、青霉素、禽菌灵等多种抗菌药物进行治疗，但效果均不理想。２　临床症状　病…