The impact of genetics on retail meat value in Australian lamb

• Selection for increased lean meat yield using Australian Sheep Breeding Values increases carcass value.
• At equal carcass weight, reduced sire breeding values for c-site fat depth increase carcass lean value the most.
• At equal age, increased sire growth breeding values increase carcass lean value the most.
• Terminal sired lambs have higher carcass lean value than Maternal and Merino sired lambs.

Lean (muscle), fat, and bone composition of 1554 lamb carcasses from Maternal, Merino and Terminal sired lambs was measured using computed tomography scanning. Lamb sires were diverse in their range of Australian Sheep Breeding Values for post weaning c-site eye muscle depth (PEMD) and fat depth (PFAT), and post weaning weight (PWWT). Lean value, representing predicted lean weight multiplied by retail value, was determined for lambs at the same carcass weight or the same age. At the same carcass weight, lean value was increased the most by reducing sire PFAT, followed by increasing PEMD and PWWT. However for lambs of the same age, increasing sire PWWT increased lean value the most. Terminal sired lambs, on average, had greater lean value irrespective of whether comparisons were made at the same age or weight. Lean value was greater in Merino compared to Maternal sired lambs at equal carcass weight, however the reverse was true when comparisons were made at the same age.