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W. T. Hall B.V.Sc. K. N. Daddow B.Sc. Corrinne K. Dimmock B.Sc. T. D. St. George M.V.Sc. H. A. Standfast B.Sc. 《Australian veterinary journal》1975,51(7):344-346
Four Merino sheep inoculated intravenously with bovine blood containing ephemeral fever virus showed no clinical signs of ephemeral fever. Two sheep showed a mild haematological response and developed a neutralising antibody which closely paralled that of a steer inoculated at the same time. Leucocytes harvested from these 2 sheep on days 3 and 4 after inoculation with virus reproduced ephemeral fever when inoculated into susceptible steers whilst those harvested on days 1, 2 and 5 did not. Even though this indicates that EFV can multiply in some sheep when they are inoculated intravenously, it cannot be inferred that natural infection occurs. 相似文献
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Adult cattle in a Queensland dairy herd with a history of deaths from lymphosarcoma were sampled regularly over a 4 year period for the identification of animals with persistent lymphocytosis (PL). Twenty-one of 94 animals that were sampled at least 6 times had PL. At the initial sampling 27% of the animals had lymphocytosis. Culling of haematologically positive animals in the first 18 months of the investigation reduced this to 5.3%, but cessation of the culling programme resulted in a gradual increase in the percentage of animals with lymphocytosis. Four deaths from lymphosarcoma occurred in adult animals, but only in the first 18 months of the investigation. Two of these animals had lymphocytosis and two lymphoblastic leukaemia. The calf of one of the latter cows developed lymphoblastic leukaemia and lymphosarcoma by the time it was 6 months of age. Although histological evidence of lymphosarcoma was lacking in a number of clinically normal animals with lymphocytosis, haematological investigation identified a group of animals within the herd that may develop lymphosarcoma. 相似文献
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Differences in the lymphoproliferative response of cattle and sheep to bovine leucosis virus infection 总被引：1，自引：0，他引：1
C K Dimmock R J Rogers Y S Chung A R McKenzie P D Waugh 《Veterinary immunology and immunopathology》1986,11(4):325-331
Lymphoblastic leukaemia, preceded by a significantly increasing percentage of prolymphocytes in peripheral blood smears for from 12 to 68 weeks before death was a feature of sheep which developed lymphosarcoma following inoculation with the Australian strain of bovine leucosis virus (BLV). Lymphocytosis and/or the appearance of immature cells were a reliable predictor of tumour formation in sheep, but not in cattle. There was a terminal lymphoblastic leukaemia in only 43 of 84 cattle with lymphosarcoma. Differences in the morphological appearance and glycogen content of the leukaemic lymphoblasts of sheep and cattle were observed. In spite of these differences the high frequency of lymphocytosis and lymphosarcoma in experimentally infected sheep suggests that they could be a useful model for studying the pathological and immunological responses to BLV infection. 相似文献
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The common endemic Australian freshwater prawn, Macrobrachium australiense is recognised as having potential as a culture species. Across the species’ natural range high variation exists for external morphological traits of relevance to culture. Previous studies have demonstrated that morphological variation can often be correlated with environmental factors. The current study demonstrated that when exposed to a controlled environment, offspring of two morphologically divergent wild stocks retain little of their parental morphological characteristics. When crossed and grown under identical conditions, ‘hybrids’ and pure offspring were morphologically uniform. A breeding and growth trial of offspring within a single stock were exposed to a variety of environmental temperatures that resulted in high variability of morphological traits in the offspring. These results suggest that environmental parameters rather than genotype may strongly influence the phenotypic expression of the morphological traits investigated. Morphological traits of interest to culture, such as abdomen length and width show low additive genetic variance and hence may not respond well to traditional selective breeding approaches designed to improve their attributes. 相似文献