Using CT scanning to breed for improved muscularity in Beltex Sheep

The Beltex breed of sheep is characterised by having double muscled hind legs and fine bones, and thus is ideally suited to producing commercial lambs for the UK market where good carcass shape and high killing out proportion are important.

These characteristics are key to the breed’s continued success. Despite its increasing importance, Beltex is amongst the few breeds that do not have an established performance recording scheme. While the importance of performance recording is widely acknowledged, there is also concern that current breeding objectives and recording focus do not address the characteristic strengths of the breed. This underlying concern is hindering the wider participation of Beltex breeders in performance recording.

This project will be vital in helping to set up a successful performance recording scheme for the Beltex breed of sheep. Given the importance of hind leg muscularity to the breed, it is very unlikely that a successful genetic improvement scheme can be developed at present unless CT scanning has been used as part of the recording process. Measurements of hindleg muscularity can be derived by using CT scanning as part of a conventional recording scheme. However, in order to obtain accurate estimated breeding values (EBVs) for hindleg muscularity, a large number of animals need to be scanned initially, with continued scanning of new animals on an annual basis thereafter. Because CT scanning is costly, and animals need to be transported to Edinburgh for scanning, breeders need to be fully committed for the recording scheme to be a success.

CT scanning has been successfully integrated into recording schemes for other terminal sire breeds following a large research project (started in 1997) in which a number of animals from each breed were scanned initially. Due its lower impact on the national sheep flock at that time, the Beltex breed were not involved in this initial project. However, the breed has seen a large growth in numbers since that time and use of the technology is now considered desirable.

Following this project the Beltex sheep Society recording scheme will also be well placed for adopting any new technology, or to adopt other EBVs that can be developed from CT scan information as part of future research.