Selection for Intramuscular Fat in Duroc Swine – An Update

Long-term progress or improvement in many economically important traits is ultimately the responsibility of the seedstock supplier. If selection progress is to be made in traits of economic importance, the trait must: 1) be accurately measurable, 2) show sufficient heritability, and 3) display an adequate level of variation. For such reasons, tremendous progress has been made in the swine industry toward increasing lean meat percentage over the past quarter century. However, in more recent years, meat quality traits have received more attention and have become more important in breeding programs as producers and processors try to meet consumer demands for high quality, nutritious products. The word quality can mean many things, but most importantly, it means customer satisfaction with pork products. Many different traits have been identified as indicators of consumer acceptance of pork and include such characteristics as color, firmness, pH, tenderness, marbling, juiciness, and flavor. Though pork quality is influenced by many factors, research has shown that between 10% and 70% of the variation in meat quality can be attributed to genetics. Specifically, intramuscular fat is reported to be moderately heritable (NPPC, 1995). Accurate measurement of all meat quality traits in the live animal is not possible; however, intramuscular fat is one of the meat quality traits shown to be accurately measured in the live animal (Ragland, 1998; Newcom et al., 2001, Newcom et al., 2002). In addition, it has favorable genetic correlations with many other meat quality traits. Greater amounts of IMF have been shown to positively impact sensory panel traits such as tenderness, juiciness, and flavor, along with mechanical measures of tenderness (Hiner et al., 1965; De Vol et al., 1988; Hodgson et al., 1991; NPPC, 1995; Huff-Lonergan et al., 2002).