Carcase and Meat Quality Attributes of Merino and First-Cross Prime Lambs

Australian prime lamb producers are being presented with an increasing number of imported breeds of sheep promoted as either maternal, dual purpose or terminal sire genotypes. There is little objective information on the carcase and meat quality attributes of the progeny of these new genotypes along with those of our established prime lamb sires. This paper reports the carcase and meat quality attributes of Merino and first-cross wether progeny from matings of Merino ewes with Border Leicester (BL), East Friesian (EF), Merino (M), Poll Dorset (PD) and South African Meat Merino (MM) sires. The 12 lambs of each breed were those selected and fed a pelleted diet prior to slaughter as described by Davidson et al. (2000). The 60 lambs were slaughtered at a commercial abattoir after 24 hours off feed. All carcases were measured for hot carcase weight (CWt), dressing percent (D %), GR tissue depth (GR), eye muscle area (EMA, m. longissimus dorsi) and muscle pH (pH). Meat colour was measured for relative lightness (L*, Colour) using a Minolta Chromameter Model CR-300. Samples of eye muscle were excised from 6 representative carcases of each breed. The 30 samples were stored frozen and later tested for tenderness by Warner-Bratzler Shear Force (WB, Bouton et al., 1971) and by a 10-member trained taste panel (Tend TTP, 0 tough – 10 tender). All first-cross lambs had significantly heavier carcases than the M lambs and the PD lambs had a higher dressing percentage than the M lambs (Table 1). The EF and M lambs had the leanest carcases based on GR and the mean GR tissue depth for all breeds was within the desired range of 6 – 10 mm. The eye muscle area of the PD and EF lambs were similar and larger than those of the other three breeds, which were not different. There were no differences between any of the breeds for muscle pH or meat L* Colour and the values were all within acceptable limits pH 32 (Hopkins et al, 1995). The MM and M lambs were the only lambs to produce meat of acceptable tenderness Table 1. Final liveweight (FWt), carcase and meat quality attributes of Merino and first-cross lambs