2.2. Body and ultrasonic measurements
Linear body measurements, namely withers height, chest girth, back length, chest depth, and pelvic width (DeBoer et al., 1974) were recorded shortly before slaughter for all animals. Withers height was measured by callipers and the other measurements were taken using a metal tape. These measurements were expressed relative to slaughter weight. Animals were also ultrasonically scanned on the right side shortly before slaughter using a Dynamic Imaging Ultrasound Scanner (model Concept IMCV, with a 3.5 MHz head). M. longissimus depth was measured at the 3rd lumbar vertebra, from the interface with the back fat layer to the bone. Four fat depth measurements were taken at the 13th rib and a further three were taken at the 3rd lumbar vertebra. The mean of these 7 values were taken as fat depth (Campion et al., 2009a).
2.3. Feed analysis
Feed analyses were carried out using the methods described by Cummins et al. (2007). Silage samples were composited for periods of 4 weeks using a bowl chopper (Muller Type MKT 204 Special, Saarbrucken, Germany).