Using CT scanning to simultaneously breed UK slaughter lambs for improved carcass and meat quality

X-ray computed tomography (CT) scanning can provide non-invasive predictions of intramuscular fat (IMF) in live lambs and meat cuts, providing potential to select for meat quality within a sheep breeding programme. The genetic control and relationships of these traits with carcass quality must be determined across relevant breeds and within the context of the new UK combined breed analysis (CBA), before recommending incorporation into existing breeding programmes. UK national data were analysed within-breed from several thousand commercial, CT scanned ram lambs of 3 terminal sire breeds, and using a snapshot of CBA data, across 7 terminal sire breeds and crossbreds. In most cases, IMF levels were moderately heritable (0.23-0.4), highly positively genetically correlated with total carcass fat and moderately negatively correlated with total carcass muscle and muscularity, although there were some marked breed differences. In a separate trial, genetic parameters estimated for IMF in meat from crossbred progeny (n=1204) of Suffolk sires (n=28), predicted by CT post-mortem, gave a similar heritability (0.21), with moderate positive genetic correlations with carcass EUROP grades for fat and conformation. Results suggest scope to use CT within a breeding programme to select for more taste and less waste in commercial slaughter lambs.