Lamb production from diverse genotypes 2. Carcass characteristics

Carcass and meat quality characteristics for 2408 cryptorchid and female la mbs at mean carcass weights of 24.8 kg and 19.3 kg respectively are reporte d. The lambs were sired by a selection of Poll Dorset (D; no. = 7), Texel ( T no. = 10), Border Leicester (BL; no. = 12) and Merino (M; no. = 12) rams and born to Border Leicester X Merino (BLM) and Merino (M) darns. The lambs comprised six genotypes (DXBLM, TXBLM, DXM, TXM, BLXM and MXM) that repres ent the range of types (second cross, first cross and Merino) produced in t he Australian lamb industry. The second cross (DXBLM, TXBLM) and first cros s BLXM were fatter than first cross (DXM, TXM) (1 mm at the GR site) and MX M (3 mm GX) carcasses at the same hot carcass weight (P < 0.01). D cross we re leaner than T cross for 24 kg cryptorchid carcasses at the C site (P < 0 .01) but there was no difference at the GX site or for 19 kg female carcass es at either site. There was no difference in M. longissimus thoracis et lu mborum (LL) area of first cross and second cross carcasses sired by D and T rams, which were proportionately 0.04 greater than MXM and 0.09 greater th an BLXM. The LL area was proportionately 0.04 greater for T than D crosses (P < 0.01). MXM had 0.02 lower dressing yield than other crosses (P < 0.01) . There was a significant genotype effect for LL ultimate pH (P < 0.01). BLXM and MXM had higher mean pH and more carcasses than the other genotypes wit h pH greater than the critical value of 5.8 for meat quality. There were no significant differences between the genotypes for chromameter measures of meat colour Implications for the production and processing sectors of the l amb industry are discussed.