Genetic and production factors that influence the content of intramuscular fat in the meat of prime lambs

Consumers are showing an increasing demand for juicy, flavoursome and tender meat, but in parallel are seeking lower fat, healthier food options. Intramuscular fat (IMF) has an important impact on palatability due to its specific contribution to juiciness and flavour and has been shown to contribute 10-15% of the variance in palatability (Dikeman, 1987). This can be compromised if the fat content is less than 3%, but is enhanced as IMF levels increase from 3-6% (Savell and Cross, 1988). Lamb contains about 4-5% IMF (Pethick et al., 2005), and studies have demonstrated that this is the level required to achieve consumer satisfaction (Hopkins et al., 2006). In recent years, increasing selection for lean growth has been linked to a decline in IMF level with subsequent detrimental effects on meat eating quality (Pethick et al., 2005). Thus maintaining sufficient levels in lamb meat is important to ensure the sensory appeal for consumers. The objectives of this study were to estimate the levels of IMF of slaughter progeny representing diverse genetic backgrounds and production systems, and to test the effect of genetic and non-genetic factors that affect IMF levels in prime lambs.