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Spatial and temporal assessment of the impact of environment and lameness management factors on footrot in English sheep flocks
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Witt, Jessica D. (2021) Spatial and temporal assessment of the impact of environment and lameness management factors on footrot in English sheep flocks. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3759484
Abstract
Footrot is an infectious disease of sheep, caused by Dichelobacter nodosus, that causes ~70% of all lameness in English flocks and has significant economic and welfare implications. Some environmental factors have been shown to affect the survival and spread of D. nodosus, including soil moisture, and soil composition. These factors can have effects on bacterial survival in the environment and establishment of disease, both individually and synergistically. On top of this, seasonal variations in air temperature and rainfall produce seasonal patterns of infection and have been associated with changes in footrot prevalence. However, evaluation of the contribution of these climate variables together with lameness management practices has not been done at the scale covered in this thesis. Furthermore, assessing the spatial and temporal variability of these patterns within England has not been yet undertaken. This study investigated the spatial distribution of annual lameness prevalence, as well as the spatial and temporal distribution of the two key phases of footrot – interdigital dermatitis and severe footrot. Hierarchal negative binomial and binomial models were then constructed to assess the effect of several climate, environment, and lameness management variables. The results confirm that there is spatial clustering in disease prevalence and a seasonal pattern seen over time, but there is still some variation in which farms exhibit significantly high or low disease prevalence year on year. This study also shows that neither the prevalence of interdigital dermatitis and severe footrot, nor their incidence of higher-than average prevalence periods, follow the same spatial or temporal patterns, and their most effective management practices are not identical. Overall, the results from this study should help farmers and veterinarians start to tailor their lameness management practices based on the farm location, time of year, and which stage of footrot is currently most prevalent in their flock.
Item Type: | Thesis (PhD) | ||||
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Subjects: | S Agriculture > SF Animal culture | ||||
Library of Congress Subject Headings (LCSH): | Footrot in sheep, Footrot in sheep -- Environmental aspects, Sheep -- Infections, Sheep -- Diseases, Lameness in sheep | ||||
Official Date: | October 2021 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | School of Life Sciences | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Green, Laura E. ; Keeling, Matthew James | ||||
Format of File: | |||||
Extent: | vii, 133 leaves : illustrations, maps | ||||
Language: | eng |
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