RamCompare, the UK’s national progeny test, launched in 2015, is a joint levy-funded project, led by AHDB.

RamCompare uses nominated performance-recorded rams from various terminal-sire breeds on commercial farms across the UK. We collect data from birth to slaughter from lambs reared in a commercial environment.

Using this robust dataset, new abattoir-derived breeding traits have been developed to provide estimated breeding values (EBVs) for carcase value such as Carcase Weight, Conformation and Fat Class, as well as Primal Yield, Meat Tenderness and Days to Slaughter, with an Overall Carcase Merit Index provided for each ram on test.

Annual results are released each spring to coincide with the start of the ram-selling season for terminal-sire breeders.

The project has been a major success and in spring last year, AHDB announced the continuation of this joint levy-funded project, with the re-launch including additional data collection and enhanced breeding values.

  • Abattoir data has been used to create a series of new breeding values, which highlight the most profitable sires
  • To-date, RamCompare has shown which traits can be used to drive productivity and optimise flock potential
  • We have identified differences in progeny values worth £4-£6 per lamb – demonstrating the opportunity that exists to enhance flock profitability through careful ram selection
  • Research has been started to assess genetic influences on primal yield and meat quality (namely tenderness)

The project has shown how commercial farmers can improve efficiency and reduce the cost of lamb production through the selection of superior rams, while providing breeders with important information to enhance their breeding policies and increase rates of genetic gain.

Results are available on the RamCompare/Signet website. Through interpretation of the results we create case studies about specific rams, breeds and farms to show the value of this work.

More information can be found at RamCompare | Signet Breeding (signetdata.com)

This work is led by Samuel Boon and Bridget Lloyd, for further information contact bridget.lloyd@ahdb.org.uk.

Beef & Lamb
Project code:
01 April 2021 - 31 December 2026
AHDB, Hybu Cig Cymru - Meat Promotion Wales (HCC), Quality Meat Scotland (QMS)
Project leader:


RamCompare Preliminary Results 2017

About this project

The Problem:

The value of commercial lambs is greatly influenced by their carcase weight and grade at slaughter and the time taken to reach slaughter weight. This attributes are greatly influenced through ram selection, which in turn influences flock profitability and the carbon footprint of lamb production.  

In the UK we are great at measuring proxy traits in pedigree, ram producing flocks. By weighing lambs and measuring them using ultrasound and computed tomography (CT) we have greatly enhanced the genetic potential of terminal sire breeds within the national flock through selective breeding.

However, the breeding values produced in pedigree flocks are still only proxy traits, measured in the live animal and believed to relate to traits of economic importance. It would be better if we were able to measure abattoir-derived traits directly and use them to produce breeding values for those attributes on which commercial farmers are paid, such as carcase weight, conformation and fat class; as well as producing a breeding value for days to slaughter, to reduce costs of production. 

A New Approach:

All Terminal Sires are now evaluated as part of a mixed breed genetic evaluation, the National Terminal Sire Evaluation. The new approach, launched in 2018, makes it much easier to analyse data from crossbred animals in both pedigree and commercial flocks, as well as facilitating a degree of breed comparison and exploiting data gathered from progeny testing programmes.

The review of genetic improvement of beef and sheep in the UK  recommended that a central progeny test (CPT) was established to collect data from commercial farms, including the collection of abattoir data.  In other countries it has been demonstrated that this approach helps to improve genetic gain when this data is incorporated into national evaluations. RamCompare was set up to put these recommendations into action for the UK.

Aims and Objectives:

  • Collect and collate data from over 6,000 lambs annually, sired by high genetic merit rams from the main terminal breeds, from several commercial farms and abattoirs
  • Collate data from a variety of sources – written records, electronic identification (EID) systems, software programs, abattoirs – in current breeding evaluations
  • Use commercial data to improve the development of the CBA
  • Investigate the relationship between on-farm measurements of performance (growth rate, ultrasound scanning of muscle and fat depth) and industry measures of economic value (carcase weight, days to slaughter, carcase conformation and fat class)
  • Explore if the genetic ranking of rams relates to cross-bred progeny, reared under forage-based commercial conditions
  • Examine how the performance of progeny of different terminal sire breeds compares under commercial conditions
  • Test the feasibility of running a CPT


A partnership of levy boards (funded by AHDB, HCC, QMS and supported by AgriSearch) was developed and maintains a close working relationship with many sheep industry representatives such as EGENES, Flock Health Ltd, Randall Parker, Dunbia, electronic data capture providers and sheep health laboratory/consultancy organisations.

Commercial flocks are selected based on robust criteria and recruited to provide data collection from their commercial lamb enterprises for a number of breeding seasons. Each farm provides a minimum of 320 commercial ewes for tupping, recording lambs at birth and following their growth through to the end of the slaughter period.

Performance recorded rams with top 20% EBVs for growth and carcase traits are nominated by Terminal sire breeders with selections being confirmed by Signet Breeding Services, AHDB.

Farms have the option to put 120-150 ewes into an artificial inseminated programme so that AI sires can be utilised and important linkage between farms can be created. All other ewes are mated in single sire groups to natural service rams. New rams/AI sires are purchased each year.

EID is used to identify the ewes and lambs are tagged and fully recorded at birth. Performance records include live and dead lambs, birth weight, gender, siblings, lambing ease, eight-week weight, 90-day weight and sale weight.

Slaughter date, carcase weight and classification is collected and carcase numbers assigned to individual EID tags.  Additional carcase information in the form of saleable meat yield and tenderness measurements were collected on a proportion of carcases during the first five years of the project.

Results - a full genetic analysis is undertaken annually with results presented in the form of tables showing the trait leading rams for live animal proxy traits (Eight-week weight, Scan weight, Muscle depth and Fat depth EBVs) and abattoir traits (Overall Carcase Merit Index, Carcase Value EBVs and Days-to-Slaughter EBVs). This allows, for the first time, rams of different breeds to be compared directly. 

Stepping into the future with phase III:

Over the next five years, RamCompare will continue to build on our knowledge of the genetic impact of ram selection on commercial lamb production. Research will be started to facilitate the routine evaluation of carcase traits within the National Terminal Sire Evaluation and by encouraging wider participation from pedigree breeders, commercial farmers and processors we intend to extend the reach of the initial project.


The commercial value of traits varies from farm to farm, but by selecting those Signet recorded sires with the right combination of EBVs, producers can identify the most profitable rams for their business.

  • High Scan Weight EBV = Increased growth rates and reduced days to slaughter
  • High Scan Weight/Muscle Depth EBVs = Increased carcase weights
  • Superior Muscle Depth/Gigot Muscularity EBVs = Enhanced carcase conformation
  • Fat Depth EBV = Reliable indicator of the fat classification achieved by sire progeny
  • High genetic merit sires demonstrate increased progeny values worth around £5/lamb which equates to £1200-£1500/ram during their working lifetime

Farmers have an opportunity to enhance flock profitability through careful ram selection but beware as few rams can do it all - some will excel for carcase conformation, others for speed of finish. Producers should evaluate their system and determine which sires have the potential to make the biggest financial impact.


Last updated: January 2022

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