Using genetic markers to detect footrot resistance

Ground-breaking research looking at the potential to breed sheep with resistance to footrot is one of the projects producers will hear about at SAC’s sheep open day at Penicuik, Edinburgh on 11 October.

Footrot is the most common cause of lameness, costing UK farmers £24m a year, and selecting sheep with improved resistance to footrot could cost-effectively improve animal health, welfare and productivity.

The incorporation of footrot resistance into structured breeding programmes will also reduce dependency on chemical solutions to control disease in farm livestock, says SAC sheep geneticist, Joanne Conington.

It is anticipated that use of zinc oxide and formalin would be greatly reduced in animal populations that are genetically resistant to footrot.

Initial results of a three-year project show there is wide variation in footrot prevalence in the offspring of different Scottish Blackface sires – some sires have no affected offspring and others up to 25% affected.

The development and use of a repeatable and objective scoring system to evaluate footrot in individual sheep is a prerequisite in the search for association with molecular genetic markers and already several thousand Blackface, Mule and Texel sheep in the UK have been scored, says Dr Conington.

A footrot test has been developed for the New Zealand sheep industry to select more tolerant or resistant animals and more than 1m sheep have already been born to rams which have been DNA-screened for footrot.

While it is possible the New Zealand test will be relevant to the UK sheep industry, Dr Conington explains work is ongoing to assess its suitability for our breeds and environment.

New Zealand has a distinctive footrot transmission period, whereas the UK typically has footrot throughout the season and also has different breeds, she says.

As a result, links between molecular genetic markers, footrot resistance and footrot-causing bacteria need to be demonstrated in the UK sheep population.