Effects of crossbred ewe genotype and ram genotype on lamb meat quality from the lowland sheep flock

A study was carried out on five lowland farms in Northern Ireland over 2 years to investigate the effects of crossbred ewe and ram genotype on lamb meat quality. Four ewe genotypes were sourced from six hill farms – Bluefaced Leicester×Blackface (BLXB), Texel×Blackface (TXB), Suffolk×Cheviot (SXCH) and Texel×Cheviot (TXCH). On each farm groups of 20–30 of each crossbred ewe genotype were crossed with Suffolk or Texel sires. Within each of the ram breeds, high lean growth index rams sourced from UK sire reference schemes (SRS) were compared with rams sourced from flocks not involved in objective genetic improvement programmes (control). Throughout the 2 years of the study the ewes lambed at 1 and 2 years of age. Lambs from each of the crosses were slaughtered at 36, 44 and 52 kg live weight. Meat from lambs slaughtered at 36 kg had lower a* values (15.1) than meat from lambs slaughtered at 52 kg (17.0 S.E. 0.47) (P<0.05). Ewe genotype had no effect on any parameter of meat quality measured. The carcasses of lambs sired by Suffolk rams had a higher pHU than lambs sired by Texel rams (5.70 v. 5.65; S.E. 0.014; P<0.05) and hue angle was lower (P<0.05) in Suffolk-sired lambs (32.9°) compared with Texel-sired lambs (35.1°) (S.E. 0.62°). Warner–Bratzler shear force was lower in SRS-sired lambs (2.05 kg/cm2) compared with control-sired lambs (2.36 (S.E. 0.096) kg/cm2; P<0.05). Carcasses from male lambs had a greater cooking loss (217 g/kg) than from female lambs (196 S.E. 5.7 g/kg) (P<0.01) and meat from male lambs had greater values for Warner–Bratzler shear force (2.44 kg/cm2) than from female lambs (1.97 S.E. 0.098 kg/cm2) (P<0.001). Low, but statistically significant (P<0.05) correlations were obtained between carcass fat measurements and meat quality parameters (r = −0.29 for the relationship between cooking loss and fat depth over the gluteus mediusP<0.001); r = 0.21 for the relationship between fat classification and C* values P<0.01). When meat quality parameters for each of the fat classes were averaged, significant linear regressions (P<0.05) were obtained between fat classification and pHU, a* and C* values.