Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659974
Title: Are scrapie-susceptible sheep more productive?
Author: Nicholls, N. A. H.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2007
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Abstract:
A relationship between scrapie susceptibility, which is determined by PrP genotype, and valuable production traits has long been noted by sheep farmers, with many claiming that their ‘best’ sheep often are found to be susceptible to scrapie, or have close siblings that are susceptible to scrapie. There have been several historical anecdotal reports to support this observation, but only recently has the hypothesis, that scrapie-susceptible sheep are more productive, been investigated in scientific study. This thesis contains the results of several such studies and is concluded by an investigation into whether the current breeding strategies being encouraged in the UK would be effective at eliminating scrapie from the national sheep flock. In these studies, PrP genotype was compared to objective measures such as lamb weights and Estimating Breeding Values (EBVs), as well as to subjective measurements which were based on a farmer’s judgement of their sheep, with varying results. Analysis of the subjective measurements, rating scores and culling records did not show any association with PrP genotype. The results of the analysis of the EBVs were variable, and inconsistent between farms, with susceptibility to scrapie being associated with both increased and decreased productivity. There was a small association between PrP genotype and lamb weights, which indicated that at eight weeks of age, ARR/ARR lambs were slightly smaller than lambs other more susceptible genotypes. Overall, however, there is no strong evidence that scrapie-susceptible sheep truly are more productive. The final section has shown that with the current suggested breeding strategies, there will still be some risk of scrapie outbreaks in some flocks.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.659974  DOI: Not available
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