Intramuscular fat content affects eating and nutritional quality of lamb meat. Muscle density measured by Computer Tomography (CT) is an in-vivo proxy measure of intramuscular fat (IMF) content that affects eating and nutritional quality of lamb meat. Lambs sired by High muscle density (HMD) or Low muscle density (LMD) rams, selected for slaughter on commercial criteria were measured for meat quality and nutritional traits. A REML model was used to compare lamb traits. Additionally, regression analysis of sire estimated breeding value (EBV) for muscle density was performed for each meat quality trait. Muscle density EBV had a negative regression with intramuscular fat content (P < 0.001). For each unit increase in muscle density EBV, there was a significant decrease in loin (-1.69 mg per 100 g fresh weight) and topside intramuscular fat (-0.03 mg per 100 g fresh weight). Muscle density EBV had a negative regression with grouped saturated and monounsaturated fatty acids concentration (and monounsaturated proportion P < 0.001). Muscle density EBV had a negative regression with loin sensory traits tenderness, juiciness and overall liking and many novel tenderness sensory traits measured (P < 0.05). Selecting for LMD EBV increased intramuscular fat content and favourable meat eating quality traits. In contrast, sire muscle density EBV had a positive regression with loin Polyunsaturated:Saturated fat ratio and grouped polyunsaturated proportion traits (including total polyunsaturated proportion, total omega-6 (n-6), total omega-3 (n-3) fatty acids (P<0.001). This is explained by the fact that as sire muscle density EBV increases, polyunsaturated fatty acid proportion increases and the proportion of saturated and monounsaturated fatty acid content decreases. Muscle density EBV had a positive regression with shear force and the novel toughness sensory traits (P < 0.05). Selection for high muscle density EBV’s increased shear force and toughness traits, which is unfavourable for the consumer. LMD sired meat had higher meat colour traits chroma/saturation (+0.64, SD 2.30, P = 0.012) redness (+0.52, SD 1.91, P = 0.012) and yellowness (+0.31, SD 1.49, P = 0.08) compared to HMD sired meat. Selection for LMD could be used within a breeding programme to increase intramuscular fat content and enhance both meat colour and improve eating quality parameters.
- sensory; trained taste panel; intramuscular fat; fatty acid composition; computer tomography