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981.
Serum antibody (virus neutralisation, complement fixation, IgM and IgG) responses to equine herpesvirus-1 (EHV-1) infection were measured in six foals which were initially free from EHV-1 and EHV-4 infection and maternally-derived antibodies. Following primary infection, high titres of virus neutralisation and complement fixation antibodies were detectable against EHV-1, however, corresponding antibody levels against EHV-4 were low or inapparent, although the two viruses share a number of cross-reactive epitopes. In addition, following the primary infection with EHV-1, IgM levels increased before those of IgG, virus neutralisation and complement fixation antibodies, peaked sooner and thereafter declined. Stimulation of IgM levels was observed on secondary infection with EHV-1 given 61 days later. In contrast, IgG, virus neutralisation and complement fixation antibodies following primary infection were more sustained and no increase in their levels was observed on secondary infection. No consistent changes in IgM or IgG levels were seen after administration of dexamethasone to reactivate latent virus. 相似文献
982.
983.
An outbreak of tuberculosis in pigs and cattle caused by Mycobacterium africanum produced lesions in the pigs similar to those caused by M tuberculosis, M bovis and M avium, with caseation in the lymph nodes of the head and in the jejunal lymph nodes. Bacteriological examination of the dysgonic mycobacteria isolated showed that they were M africanum I. The intradermal tuberculin test was very reliable in pigs, differentiating between mammalian and avian reactions, and the results of the test were in accordance with the lesions found at meat inspection. No clinical signs were observed during the outbreak, and the infection was neither serious nor progressive. There were no lesions in the tuberculin-positive cattle. The source of the infection remains unknown. 相似文献
984.
985.
Howard A. Clonts Curtis M. Jolly Syed Abdulkadir L. Alsagoff 《Journal of the World Aquaculture Society》1989,20(4):268-276
The merits of integrated aquaculture farming (IAF) as a strategy for bolstering income for the rural poor have been recognized, but the economic efficiency and sustainability are yet to be determined. The effects of one species on another and the economic benefits, net of government support, have not been critically evaluated. The concept of a foodniche for alternative species in an aquatic environment has not been properly tested in an economic setting. Thus, this report reflects the results of applying the technique of mixed integer linear programming to determine the optimum combination of species within the context of a foodniche. The objective also included maximizing revenues, with minimal external input requirements, for a representative small Malaysian wet-rice farm. It was found that the foodniche concept permitted flexibility in stocking rates, and that farmers could actually stock species at the exact rate that was optimal for profit, instead of standard fixed rates. Also, government subsidies for pond construction were essential for IAF success. The net revenues from IAF were low without interest-free loans for pond construction. 相似文献
986.
M. Bhalov 《EPPO Bulletin》2004,34(3):365-367
Erwinia amylovora has been spreading in the Czech Republic since 1986 regardless of emergency phytosanitary measures which have been taken. Its spread follows the predominant wind direction (west to east). The infested area now covers two thirds of the area of the country. Wild Crataegus spp. are the most important and widespread host plants. E. amylovora is still regulated as a quarantine pest, and areas free from fireblight are subject to special phytosanitary measures. 相似文献
987.
988.
Long‐term experiments are a classical case of repeated measurements. Traits are measured on the same experimental unit over many years so that correlations arise between the observations made on the same plot in consecutive years. This paper describes the analysis of a three‐crop‐rotation long‐term experiment. We analysed the yields of the crops and the organic carbon content in the topsoil over 30 consecutive years. Several variance–covariance approaches are discussed and the trait‐specific best fit is interpreted. Mixed models are used to describe the structure of the experiment. Both yields and soil organic carbon show a more or less pronounced variance heterogeneity. Especially for yields, the heterogeneity of cycles and years is dominant. The consideration of correlations results in a better model fit in all cases. 相似文献
989.
990.