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In 2013 Signet supported an initiative developed by the Suffolk Society’s Performance Recording Committee to look at ways of strengthening genetic linkage within the Suffolk evaluation. This article reports back on that trial.

Within the Suffolk breed the selection of rams with superior EBVs has helped the breed to make high rates of genetic gain in commercially important traits such as growth rate and muscling. Whilst few would deny the achievements made in recorded flocks there were concerns that for flocks interested in joining the scheme:

  • Good sheep of unknown genetic merit would be unfairly held back
  • New recording breeders wouldn’t be able to “catch up” with those with more records
  • It would be difficult to achieve sufficient flock to flock linkage (through shared genetics) to enable fair and accurate comparisons


The trial involved three well recorded Signet flocks (Huish, Bentley & Perrinpit) and three that were not actively involved in recording (Pexhill, Sitlow & Rookery). Within breeding evaluations any sire can be used to create genetic linkage between flocks – although traditionally one with high EBVs is often used. For the purposes of this trial the “reference” sire was a high value unrecorded stock ram, whose genetics were proven in the show ring – which all parties agreed was of a highly acceptable breed type.


Flock to Flock Linkage

In general high levels of linkage were established between the six flocks, the linkage between the Bentley and Perrinpit flocks and the three previously non-recorded flocks was higher than that achieved by the Huish flock (which had the smallest number of reference ram progeny).
The table below shows the flock to flock linkage – with values over 0.025 being regarded as “green” and providing linkage strong enough to make good comparisons between individual flocks.

The take home message from this work is that breeders can achieve considerable amounts of genetic linkage within a single year to enable solid comparisons of the genetic merit of lambs reared in different flocks.