Published online by Cambridge University Press: 20 November 2017
Performance recording schemes for sheep flocks in the UK incorporate ultrasonic scanning to measure criteria that are linked to carcass lean content as a selection objective (Simm, 1998). In Wales, under the direction of the Welsh Sheep Strategy, fat and muscle depth has been monitored routinely in hill flocks but with a range of ram ages at scanning (Anderson, 2000; Ap Dewi, unpublished). The date of scanning is often dictated by timings of routine tasks within the flocks so there is a need to explore the impact of time of scanning on the measurements obtained. The objectives of the investigation were to study how muscle and fat depths changed over a series of scanning dates.