Genetic analyses of novel traits derived from CT scanning for implementation in terminal sire sheep breeding programmes

•New CT traits associated with eye muscle, spine and intramuscular fat were studied.•Across three breeds, new CT traits were generally moderately heritable.•At a fixed live-weight, carcass traits were more heritable than at a fixed age.•Unfavourable correlations in spine traits versus muscling, and between fat depots.•Findings could contribute to the production of new terminal sire selection indices.