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Adjusting the scale of the Hill Sheep Index

In 2022 we launched the Hill Sheep Breeding Index to help the buyers of hill rams to identify the most profitable sires for their flock. The index is doing a great job identifying those rams whose daughters will successfully rear fast growing lambs, with good conformation whilst avoiding large increases in ewe mature size.

Our hill sheep breeding programme includes data from 14 breeds. Within the Welsh Mountain breed we record over 10,000 lambs/annum, including a number of different strains of Welsh Mountain that have been bred to thrive under different upland environments.

Over the winter we have looked at the way the index is expressed to assist with the marketing of hill rams, and particularly those hill sheep that due to strain differences may sit a little lower in the overall rankings.

To support ram breeders in 2024 the index will be rescaled to better reflect the variation within the population, whilst operating from a higher initial starting point. The ranking of rams will not change, but the average index within each breed will be closer to £10 than the current starting point of £1.

Breed Benchmarks for the Welsh Mountain and Scottish Blackface breed are shown below to highlight how the values have changed.



Index for Top 10%

Average Index

Index for Bottom 10%

Welsh Mountain










Scottish Blackface









Note: Indexes can’t be compared between breeds.

This change will influence all animal records, current and historic in the same manner. Indexes can be compared within the evaluation that is currently published on the Signet website – but you can’t compare the re-scaled index with those indexes produced in previous years. If you would like a new copy of your flock records with these changes implemented, please contact Signet directly [email protected].

This small, but important change in index presentation will help the way in which rams are marketed, regardless of where a flock sits within the national hill sheep evaluation – as well a future proofing the service for the inclusion of more genotypes in the years to come. 

For more information email: [email protected]

About the author

Samuel Boon

Samuel Boon

I am the Manager of Signet Breeding Services, within the AHDB.

Enthusiast on all things genetics to do with sheep and cattle and currently also supporting Bridget Lloyd in running the @RamCompare progeny test with ~18,000 lambs/annum.

I am also involved with the:-

  • Relaunch of Terminal Sire Breeding Programmes (Sheep)
  • AHDB lead for the Welsh Sheep Breeding Project run by HCC - working with Innovis, HCC and Janet Roden
  • Database design and development for this website
  • National Sheep Breeds Survey
  • Development of Carcase Trait EBVs in Beef Cattle
  • Formerly involved with the delivery of the Welsh Sheep Strategy, Northern Upland Sheep Strategy, Suckler Cow Project, Highlands and Islands Sheep Strategy

I can be followed on Twitter @SamBoonBreeding