The goal of the study is to exploiting the host’s genetic susceptibility/resistance to infections with virulent strains of D. nodosus causing clinical signs of footrot. Until now, linking footrot phenotype to genetic markers of the sheep has not yet been undertaken in any Swiss breed. The aim of this study is to investigate if existing significant genetic markers are related to clinical signs of footrot and the presence of an infection with virulent strains of D. nodosus in a cohort of Swiss White Alpine sheep, a breed to which nearly every second sheep in Switzerland belongs. This study should be considered as an initial attempt to go towards identifying genetic markers that are associated with footrot resistance in sheep which will be useful for future breeding decisions. However, we recognize that the current genetic test (Lincoln University footrot gene test) that is already available from New Zealand for detecting footrot resistance (Hickford et al. 2004) is most likely not be applicable to Swiss breeds because, a) having polymorphisms that are not recognized by the test, and b) existing test categories not conferring the same degree of resistance under Swiss conditions.
The development and use of a molecular genetic test for footrot resistance potentially has enormous advantages. This is because of the practical difficulty of objectively scoring feet lesions well, and the difficulty of classifying them objectively and repeatable. In addition, with genetic markers, animals that are candidates for selection do not have to be exposed to infection to determine whether they are genetically susceptible or not. Additionally, this method can shorten the generation interval and accelerate responses to selection, and potentially offer a practical alternative to measurement protocols that require exposure to infection. The proposed project will be possible to determine whether or not breeding for enhanced footrot resistance is a practical, feasible and economic option for Swiss sheep farmers. A successful selection of sheep with improved resistance to footrot is likely to be cost-effective and will contribute to increased sustainability by improving animal health, welfare and productivity. The incorporation of footrot resistance into structured breeding programmes will reduce the dependency on chemical solutions to control disease in farm livestock. For example, it is anticipated that the use of zinc sulfate, copper sulfate and formalin would be greatly reduced in animal populations that are genetically resistant to footrot. Furthermore, a genetic test for detecting resistant sheep would have the potential to prevent an increase of antibiotic treatments.
