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At least 577 records · Page 32Linked to original sources
PubMed2006

The effect of Johne's disease on production traits in Romney, Merino and Merino x Romney-cross ewes.

AIM: To quantify the effects of clinical Johne's disease on the performance of Romney, Merino and Merino x Romney-cross ewes. METHODS: The performance of ewes was compared using eight birth cohorts (1971-1978). Merino and Merino-cross genotypes included New Zealand Merino and Australian Superfine Merino sources. Intensive monitoring of Johne's disease was undertaken over the production years 1975-1982. Positive diagnostic evidence of Johne's disease was established post mortem from lesions of granulomatous enteritis associated with high numbers of acid-fast bacilli. Over years, data on a total of 2,341 Romney ewes and 1,292 Merino and Merino x Romney-cross ewes were recorded, consisting of annual records of liveweight (LWT), greasy fleece weight (FWT), number of lambs born per ewe per year (NLB), and lifetime productivity of ewes. RESULTS: A total of 82 (3.5%) Romney ewes and 62 (4.8%) Merino and Merino x Romney-cross ewes were diagnosed with clinical Johne's disease over the 8-year monitoring period, equivalent to 0.9% and 1.2% annual cases for these breeds, respectively, of the ewes present at mating. The percentage of clinical cases (p<0.04) and the age at death from Johne's disease (p<0.02) were lower for Romneys than for Superfine Merinos. The mean age of death from Johne's disease was 3.41 (standard error (SE) 0.06) years, lower than the mean disposal age from the flock of 5.03 (SE 0.02) years for clinically normal ewes (p<0.001). In their final year of production, ewes with clinical Johne's disease had lower LWT by 5.3 kg (10.5% of the mean; p<0.001), lower annual FWT by 0.54 (SE 0.10) kg (14.2%; p<0.001), fewer NLB by 0.15 (SE 0.07) lambs (13%; p<0.05), and lower litter weaning weights by 3.6 (SE 1.3) kg (15%; p<0.01) compared with clinically normal ewes. The size of the production losses associated with Johne's disease depended on the age to which ewes survived. Considering all production years of ewes (up to 8 years), the total weight of lambs weaned by ewes with clinical Johne's disease was 30.9 (SE 3.4) kg lower (46%; p<0.001) than the total from clinically normal ewes. CONCLUSIONS: Clinical Johne's disease led to significant losses in LWT, FWT, NLB, and in the lifetime production of ewes, amounting overall to a 46% reduction in productivity (p<0.001). CLINICAL RELEVANCE: Productivity losses from clinical cases of Johne's disease would be of considerable economic importance in flocks with a high incidence of the disease. The lack of good diagnostic tests for Johne's disease in the live animal, and the lack of active surveillance programmes, has made it difficult to establish the true prevalence of Johne's disease in sheep flocks in New Zealand, and its economic consequences.

Age Factors↗
PubMed2005

Pathogenesis of astrovirus infection.

Astroviruses are one of the leading causes of diarrhea worldwide. In spite of its impact on human health, little is known about astrovirus pathogenesis. One reason for this may be the lack of a suitable small animal model for infection. In recent years, there has been increasing information on the mechanism of astrovirus-induced disease in mammals (including humans) and birds. This review summarizes our current state of knowledge on astrovirus pathogenesis.

Animals↗
PubMed1981

Structural characteristics of nairoviruses (genus Nairovirus, Bunyaviridae).

Viruses from six antigenic groups of arthropod-borne viruses [Crimean--Congo haemorrhagic fever (CCHF), Nairobi sheep disease (NSD), Qalyub (QYB), Sakhalin (SAK), Dera Ghazi Khan (DGK) and Hughes (HUG) serogroups], some previously categorized as bunyavirus-like viruses and others previously ungrouped, have recently been assembled by serological analyses into a new genus of viruses (Nairovirus genus) in the Bunyaviridae. Molecular studies of the virion RNA and viral polypeptides have been undertaken with representative members of the different serogroups [Hazara (HAZ) and Congo (CON) viruses, CCHF group; Dugbe (DUG) virus, NSD group; QYB, Omo and Bandia (BDA) viruses, QYB group; Avalon (AVA) virus, SAK group; DGK and Abu Mina (AM) viruses, DGK group; and HUG virus, HUG group]. In agreement with a recent study of QYB virus and in part agreement with an earlier report on DUG virus, the results of these molecular analyses indicate that nairoviruses have: (i) three virion RNA species (large, L, medium, M, and small, S) with apparent mol. wt. of 4.1 x 10(6) to 4.9 x 10(6), 1.5 x 10(6) to 1.9 x 10(6) and 0.6 x 10(6) to 0.7 x 10(6) respectively; (ii) a 48 x 10(3) to 54 x 10(3) mol. wt. nucleocapsid (N) polypeptide; and (iii) two external glycopolypeptides, 72 x 10(3) to 84 x 10(3) mol. w. (G1) and 30 x 10(3) to 40 x 10(3) mol. wt. (G2). Cross-immune precipitation analyses have confirmed that viruses in the Nairovirus genus share antigenic determinants and are antigenically distinct from representative members of th Bunyavirus, Phlebovirus and Uukuvirus genera (Bunyaviridae).

Antigens, Viral↗
PubMed2003

The influence of ovine MHC class II DRB1 alleles on immune response in bovine leukemia virus infection.

We have reported previously that the alleles of the ovine leukocyte antigen (OLA)-DRB1 gene that encode the Arg-Lys (RK) motif and the Ser-Arg (SR) motif at positions beta70/71 of the OLA-DRbeta1 domain are associated with resistance and susceptibility, respectively, to development of bovine leukemia virus (BLV)-induced ovine lymphoma. Here, to investigate the different immune response in sheep that carried alleles associated with resistance and susceptible for 30 weeks after infection with BLV, we selected sheep that had the RK/RK or SR/SR genotype among the 52 sheep analyzed by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing of PCR product for the OLA-DRB1 exon 2 and infected them with BLV. Although the number of BLV-infected cells and virus titer had been maintaining low levels throughout the experimental period, the sheep with the RK/RK genotype could induce expansion of CD5- B-cells and rapid production of neutralizing antibody in the early phase of infection. The level of incorporation of [3H]thymidine by peripheral blood mononuclear cells from the sheep with RK/RK genotype gave a strong response to BLV virion antigen and synthetic antigenic peptides that corresponded to T-helper epitope of the BLV envelope glycoprotein gp51. In contrast, the sheep with SR/SR genotype showed a strong response to BLV virion antigen and synthetic antigenic peptides that corresponded to T-cytotoxic and B-cell epitopes. In such cases, the animals with the RK/RK strongly expressed IFN-gamma, the animals with SR/SR genotype strongly expressed IL-2. To determine the proliferating cells, we tried a blocking assay with monoclonal antibodies such as anti-CD4, -CD8 and -DR molecule. We found that these proliferating cells were MHC-restricted CD4+ T-cells.

Alleles↗
PubMed2002

Relating national veterinary services to the country's livestock industry: case studies from four countries--Great Britain, Botswana, Perú, and Vietnam.

At the end of WW II, the British Government of the time decided that it was essential for Britain to become self-sufficient in food. In consequence there was a large investment in services to agriculture and in particular many new veterinary investigation centers were opened to help farmers produce more animal products. The upsurge in world trade led the Government of Mrs. Thatcher to decide that livestock was just another commodity and so there has been a massive scaling down of money available to assist the livestock farmer. For Botswana the livestock industry is vital to the well-being of the people and successive Governments have continued to invest in veterinary services. As a consequence, Botswana has one of the best and most efficient Veterinary Services in Africa. By contrast, the livestock industry in Perú has an insignificant effect on the gross national product. The fiber exports from camelids are a small international market, while the dairy industry is unable to provide sufficient milk for the nation. Partly as a result of this, the Peruvian Government invests very little in the livestock industry or the veterinary services that support it. Vietnam is in a transitional stage: there is a large but as yet unorganized livestock industry with a mass of smallholder farmers. The Government has made a large investment in people in the Department of Animal Health but without a concomitant investment in equipment and training. If the industry is to develop, it will require much more investment from the government. These countries will be discussed in more detail and an attempt will be made to show how by relating the services to the livestock industry, governments can improve services and at the same time cut the costs.

Animal Diseases↗