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Pathogenic E. coli infections cause approximately one quarter of disease losses in commercial turkey flocks. A small subgroup of E. coli causes most infections. Epidemiologic studies of this disease have been hindered by a lack of reliable markers to discriminate between pathogenic and fecal E. coli and by the diversity of poultry strains. Reliance on antimicrobials to control E. coli infections has caused widespread antimicrobial resistance. One hundred five clinical E. coli were obtained, and 1104 isolates were collected from fecal specimens of 20 flocks in an integrated turkey operation. Biochemical fingerprinting and antimicrobial susceptibility tests were performed on all isolates, and somatic antigen serologic testing and PCR for potential virulence genes were conducted on 299 strains including all clinical isolates and fecal isolates that had similar traits to clinical isolates. Most avian E. coli infections were caused by a few clonal strains that were uncommon in normal fecal flora. The potential virulence genes iss, K1 and tsh were detected more frequently among clinical than fecal isolates; however, the pattern of occurrence did not suggest that these genes were useful markers for identifying pathogenic strains. Syndromes consistent with colibacillosis were the most commonly reported illness and principal rationale for antimicrobial therapy in sampled flocks. Most clinical E. coli isolates were resistant to gentamicin, sulfamethoxazole and tetracycline. Although resistance to fluoroquinolones and β-lactam antibiotics occurred less frequently, the potential for resistance to emerge to these antimicrobials was evident. A Bayesian model to estimate sample size confirmed the diversity of avian fecal E. coli strains. Studies are needed to define risk factors for infection with and identify markers for avian pathogenic E. coli strains. These research priorities are complementary and may lead to the identification of new interventions to prevent this important infectious disease of poultry. / Ph. D.

Intensive agricultural developments and increasing human population has caused severe lowland-forest loss and fragmentation in the western coastal plain in Taiwan over the past centuries. The goal of this study is to explore the multiscale impacts of forest fragmentation on species richness and community composition of lowland-forest birds in Taiwan. At a regional scale, Island Biogeography Theory was applied to examine area and isolation effects on species richness of lowland-forest birds using bird data derived from Breeding Bird Survey Taiwan in 2009 and 2010. I also investigate the differential responses of two functional groups (forest specialists and generalists) to area and isolation effects Furthermore, I examine the relative influences of environmental variables at regional, landscape and local scales on avian community indices and composition in northern Taiwan with a hierarchical multiscale approach. Finally, species vulnerable to forest fragmentation and the ecological traits associated with specie vulnerability to forest fragmentation were identified. Only forest specialist species responded to the regional-scale area and isolation effects. The species richness of forest specialists increased with the size of forest islands, and the community similarity of forest specialist species declined with increasing the distance from the sources of immigrants. Structurally isolated forests may not function as real habitat patches from the view of forest generalists because of their flexibility in utilizing the non-forest matrix. After accounting for the influences of environmental variables at other spatial scales, the regional-scale isolation effect still played a key role in determining avian community composition based on the  presence/absence data set. But local-scale forest condition also explained a considerable amount of variability in the presence/absence data set. The regional-scale isolation effect, however, didn't show significant influences on community composition based on the abundance data set. In contrast, the landscape-scale variables explained the largest amount of variability in the abundance data set at the entire community level. There were six bird species (Parus varius, Dicrurus aeneus, Treron sieboldii, Pericrocotu solaris, Erporniszan tholeuca and Alcippe brunnea) whose occurrence and abundance were both vulnerable to forest fragmentation. Habitat specialization was the ecological traits most strongly associated with their vulnerability / Ph. D.

Abstract AI (Avian Influenza) it is originally a kind of epidemic disease infecting among the poultry, once the poultry are infected with the Avian Influenza, will cause high death rate and even the poultry do not die and recover may cause productivity drop : laying hens decrease egg production, breeders reduce hatchery, broilers have poor weight gain, therefore increase the farmers producing cost. And in order to prevent Avian Influenza farmers have to avoid infecting and use the right vaccines. But the Taiwan environment is open disinfectant can do not much . The directly effective method is to use the vaccines.But Taiwan no one produces the vaccines at present, the government has not allowed vaccines to import yet either. Even government allow to import but there are too many serum types of the Avian Influenza, and the types do not have cross protect , let farmers have no effective method to prevent the Avian Influenza. once the avian got infection the farmer losses much. The Avian Influenza happens for many years in the poultry, with the time and mutation of the virus, the Avian Influenza become to high pathogenic Avian Influenza (High pathogen Avian Influenza, is abbreviated as HPAI) and infect to the human being . The poultry industry is very important in the animal husbandry of Taiwan, occupy the important position in agricultural production. NowTaiwan farmers not only have to face the internal Avian Influenza infection problem but also to face the step that opens with the internationalization of accession to the WTO. The animal husbandry of Taiwan has produced and faced the serious impact. Though high pathogenic Avian Influenza did not happen in Taiwan yet, but some parts of the world release the case of infecting successively, some cases even cause death. World Health Organization (WHO, World Health Origanization) monitor and control tightly, and prophesy Avian Influenza will lead to the fact that prevails greatly. This research studies the past events in the animal livestock and finds the effect and change of the market. Also use SWOT to know present animal livestock situation.And then to know the changes of high pathogenic Avian Influenza happened in Taiwan (HPAI, High Pathogen Avian Influenza), Finally gives some recommend and strategy to G company. Key words: AI (Avian Influenza), HPAI, High Pathogen Avian Influenza, WTO, Animal production, Strategy

No description available.

Thesis (D.P.H.)--University of Michigan.

Thesis (M.P.A.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 86-88).

Thesis (M.P.A.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 86-88). Also available in print.

Dissertation (D.P.H.)--University of Michigan.

No description available.