PASSIVE TRANSMISSION OF CAMPYLOBACTER FETUS BY IMMUNISED BULLS

Two groups of 24 heifers were mated with 3 immunised and 3 susceptible bulls respectively. Six heifers in each group were infected artificially with Campylobacter fetus sub-sp. fetus biotype venerealis. Among susceptible heifers mated with immunised bulls, 13/18 became pregnant and 5/18 yielded evidence of infection with C. fetus. Among susceptible heifers mated with susceptible bulls, 7/18 became pregnant and 10/18 yielded evidence of infection. C. fetus was isolated on one occasion from an immunised bull, but the immunised bulls failed to develop carrier status and one was shown to be refractory to artificial challenge. Susceptible bulls developed carrier status during the breeding period. It is suggested that passive transmission of C. fetus by immunised bulls can occur under conditions of intensive sexual activity.     

THE INFLUENCE OF AGE ON THE SUSCEPTIBILITY OF BULLS TO CAMPYLOBACTER FETUS SUBSP VENEREALIS

Observations were carried out on 22 Hereford bulls to determine the age at which they bacame carriers of C. fetus. During preliminary investigations, 5 bulbs were repeatedly exposed to the organism by artificial or natural means from the age of 18 months. All animals became longterm carriers on reaching an age of between 40 and 70 months. Prior to this, a temporary carrier state lasting from 4 to 29 days was produced in 4 bulls. In a subsequent experiment, 17 bulls of 3 different age groups were artificially exposed to C. fetus on 5 occasions over a 2-year period. Thirteen bulls became long-term carriers, including 9 (53%) when less than 4 years old. A transient carrier state occurred in 4 bulls, 2 of which subsequently became long-term carriers. It usually lasted 1-2 weeks, although in 1 animal the organism persisted for 11 weeks. These results are discussed in relation to the findings of other workers and it is concluded that the use of young bulls to limit the spread of C. fetus in infected herds is of dubious value.     

IMMUNISATION OF CATTLE AGAINST VIBRIOSIS WITH VACCINES PREPARED FROM CAMPYLOBACTER FETUS SUBSP FETUS

Subcutaneous administration of vaccines prepared from cells of Campylobacter fetus subsp fetus strain A28 to heifers gave substantial protection against infertility due to C. fetus subsp venerealis strain B6. Strains A28 and B6 had different heat-stable antigens and conformed respectively to serotype B and serotype A of Berg et al (1971). The results suggested that the protective antigens were heat-labile antigens common to both strains. Although vaccines prepared from serotype B strains of C. fetus subsp fetus could be used to immunise cattle against vibriosis, the results did not suggest that their use in preference to those prepared from C. fetus subsp venerealis would offer any advantages.     

干热空气处理防治家蚕微粒子病胚种传染的研究

采用干热空气对广东现行10个家蚕品种进行热处理,结果表明,蚕卵产后常温（25～27℃）保护12h,46℃热处理60min或47℃热处理40min,不影响实用孵化率,而对微粒子病胚种传染的防治效果达到93％～100％;蚕卵的溶菌酶和超氧化物歧化酶（SOD）,过氧化物酶（POD）,过氧化氢酶（CAT）等三种保护酶系统活力均升高;电子显微镜观察到治愈病卵正常发育至蚁蚕,未经热处理的病卵产下132h后形成孢子,孵化出带病蚁蚕。     

空肠弯曲菌产肠毒素性的研究

通过间接ＥＬＩＳＡ法和ＣＨＯ细胞法和２８６株空肠弯曲菌产生细胞紧张性肠毒素（Ｃｙｔｏｔｏｎｉｃ Ｅｎｔｅｒｏｔｏｘｉｎ,ＣＥ）的检测,ＣＥ的栓出率分别为２４．５％和１２．２％,间接ＥＬＩＳＡ法的敏感性明显高于ＣＨＯ细胞法（Ｐ〈０．００１）,并且特异性较高,即证实间接ＥＬＩＳ法检测,来自健康蛋白鸡、健康后备蛋鸡、腹泻死亡后备蛋鸡、腹泻后备蛋鸡、腹泻死亡仔猪、腹泻仔猪、健康羔羊和腹泻口才菌株的ＣＥ检出     

PREPARATION OF TEASER BULLS BY DORSAL SCROTAL PENILE DEFLECTION

SUMMARY A simple, quick and reliable technique of preparing teaser bulls has been developed. Four Bos indicus bulls aged between 1 year 6 months and 2 years were subjected to this method by deflecting their penes backwards about 2 to 3 cm posterior and dorsal to the attachment of the scrotum. No serious postoperative complications were recorded. The sexual behaviour and libido of the bulls did not change after subjecting them to this technique.     

斑点酶联免疫吸附试验诊断猪囊虫病的研究

通过Sephadex G-200层析提纯猪囊虫的囊液抗原和匀浆抗原,并以此抗原建立Dot-ELISA法来诊断猪囊虫病。该法在接到病料后1.5h内准确报告结果,结果判定不但简易直观,而且还可以作为技术资料长期保存。本法以硝酸纤维素膜作为载体,抗原用量、其他器材和试剂用量都大为减少,因而降低了检测成本。与四种寄生虫病(旋毛虫、弓形虫、细颈囊尾蚴、猪蛔虫)阳性血清不发生交叉反应。对按“四部”规程肉检确认为猪囊虫阴性血清42份,阳性血清17份,经 Dot-ELISA 法检测,其阴性符合率为95.24%,阳性符合率为100%,经三次重复,重复率为100%。对西宁市肉联厂的536份商品猪血清进行检测,其猪囊虫病阳性检出率为4.29%。试验结果证明,该法符合“简便、快速、敏感、准确、经济”的原则,尤其易于在基层推广应用。     

鸡传染性法氏囊病病毒经饲料传播的研究

用病毒分离、血凝与血凝抑制试验、琼脂扩散试验、夹心ＥＬＩＳＡ、ＲＴ－ＰＣＲ及ｃＤＮＡ探针斑点杂交试验等六种方法对一起罕见疫情的传入途径进行了调查。病毒分离和ＲＴ－ＰＣＲ试验证明，这是由于鱼粉中污染有鸡传染性法氏囊病病毒所致。本研究结果提示，ＲＴ－ＰＣＲ是进行鸡传染性法氏囊病病毒传播途径研究的首选方法，应加强饲料的兽医卫生监督管理，探讨把重要疫病病原列入质检项目的可行性。     

用卵黄Skirrow平板调查家禽空肠弯曲菌

选用卵黄Ｓｋｉｒｒｏｗ＇ｓ平板及烛缸法加焦性没食子酸制备的微需氧环境，对来自家禽的６５３份样品样进行了空肠弯曲菌的分离培养。其中，鸭盲肠内容物带菌率为７７．３％（８５／１１０）；鸡粪样带菌率３４．８％（４０／１１５）；鹅泄殖腔带菌率３１．７％（　／１０１）：并对３２７份鸭胴体进行了污染情况调查。结果表明：鸭不仅带菌率高屠宰加工过程中肉品污染较严重（２７．２％，８９／３２７）。试验证实：卵黄Ｓｋｉｒｒｏｗ平板及本试验选用的制激需氧环境方法能满足空弯菌对营养及微需氧要求。同时，在检验程序上用增菌法优于直接法（Ｐ＜０．０１），可提高检出率，我们认为这种方法值得推广。