Lamb production from diverse genotypes. 2. Carcass characteristics

Abstract

Abstract Carcass and meat quality characteristics for 2408 cryptorchid and female lambs at mean carcass weights of 24·8 kg and 19·3 kg respectively are reported. 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 × Merino (BLM) and Merino (M) dams. The lambs comprised six genotypes (D×BLM, T×BLM, D×M, T×M, BL×M and M×M) that represent the range of types (second cross, first cross and Merino) produced in the Australian lamb industry. The second cross (D×BLM, T×BLM) and first cross BL×M were fatter than first cross (D×M, T×M) (1 mm at the GR site) and M×M (3 mm GR) carcasses at the same hot carcass weight ( P < 0·01). D cross were leaner than T cross for 24 kg cryptorchid carcasses at the С site ( P < 0·01) but there was no difference at the GR site or f or 19 kg female carcasses at either site. There was no difference in M. longissimus thoracis et lumborum (LL) area of first cross and second cross carcasses sired by D and T rams, which were proportionately 0·04 greater than M×M and 0·09 greater than BL×M. The LL area was proportionately 0·04 greater for T than D crosses ( P < 0·01). M×M 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). BL×M and M×M had higher mean pH and more carcasses than the other genotypes with 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 lamb industry are discussed.