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Selective Breeding For Scrapie Resistance In Sheep

Published: Wed, 05 Jan 2005

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Research Note Full Title

Selective breeding for scrapie resistance in sheep
The National Scrapie Plan aims to reduce and eventually eradicate small ruminant-TSEs (scrapie-like diseases) from the national sheep flock by selecting on PrP (scrapie resistance) genotypes.  However, a focus on scrapie genotype alone is risky if favoured alleles are antagonistic to other important traits or sufficiently rare that their selection leads to important losses in genetic variability.  Selection for scrapie resistance thus must fit within an overall genetic improvement scheme.

Objectives

Defra have recently begun funding a research project to assess the link between breeding for scrapie resistance in sheep and other important traits.  The project, which is entitled ‘Selective breeding on PrP genotype in the UK sheep flock: evaluating the consequences and deriving optimal strategies’, started in January 2004 and will run for four years.  It is jointly led by SAC and the Roslin Institute.

The overall objectives of the project are to:


  • Collect and analyse the information necessary to critically evaluate the impact of widespread selection on PrP genotype in the UK sheep population
  • Devise optimal breeding strategies for scrapie resistance in the context of an overall genetic improvement programme
  • Make recommendations and disseminate results to the sheep industry

Approach

Data component

The data to be analysed in the project are coming from two main sources: data that already exists, including:experimental data collected from flocks held by a number of the research partners (SAC Suffolk, SAC/Roslin Institute, Scottish Blackface and ADAS Swaledale)commercial data held mainly by Signet/MLC. Where possible we will also use data from traditional and rare breeds of sheep enhanced data collection:additional data relating to lamb survival and health disorders will be collected from representative breeds from each major sector of the UK sheep industry.

Outcomes

Implications

These data will be used to:

  • assess associations between PrP genotype and production, health and adaptation traits
  • monitor the continued impact of the National Scrapie Plan on such traits
  • obtain reliable estimates of the frequencies of different PrP genotypes

Future Work

Modelling component

Computer modelling will be used to design optimal breeding strategies for scrapie resistance and to study the dynamics of scrapie infection. Modelling will be informed by data collected and analysed in the project. Special reference will be given to:

  • the expected success of different strategies in achieving resistance to scrapie
  • their impact on genetic variability
  • their impact on genetic merit for other important performance characteristics

Sponsors & Partners

Research Sponsors

Department for Environment, Food and Rural Affairs (Defra)

Research Partners

Roslin Institute, University of Edinburgh,University of Wales, Meat and Livestock Commission, Veterinary Laboratories Agency, ADAS, Rare Breeds Survival Trust, The Sheep Trust, CBS Technologies, Virginia Polytechnic Institute and University (USA)

Contact

Dr Tim Roughsedge
SAC (Scottish Agricultural College) Work SAC, Roslin Institute Building, Easter Bush
Midlothian
EH25 9RG
TelWork 0131 5353225/6519344
Fax 0131 535 3121

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