Effects of Breed and Genotype
Scientific evidence suggests that non-genetic effects, such as pre-slaughter diet, have much
greater influence on beef flavor than do additive and non-additive genetic effects (Gregory et
al., 1994). Heritability estimates reported for beef flavor intensity (Gregory et al., 1994;
Wheeler et al., 2001; Riley et al., 2003; Nephawe et al., 2004; Dikeman et al., 2005) typically
have been very low (0.04 to 0.07), suggesting that less than 10% of the variation in beef flavor
may be attributed to additive genetic effects. Even though a few reports (Wheeler et al., 2004,
2005) indicate that beef flavor may be moderately heritable (h2 = 0.26 to 0.40), direct selection
for improved flavor characteristics is impractical due to the difficulty and cost of measuring
phenotype. Additionally, comparisons across a broad spectrum of cattle breeds and biological
types have revealed few meaningful differences in beef flavor (Koch et al., 1976, 1979, 1982;
Wheeler et al., 1996, 2001, 2004, 2005), suggesting that preferential use of specific breeds to
improve beef flavor has very limited potential.
The minor among-breed flavor differences that have been documented (Figure 6) tend to be
moderately correlated with breed differences in marbling (Gregory et al., 1994). Marbling is a
moderate to highly heritable trait (Ritchie, 2005). Furthermore, moderate to strong, positive
genetic correlations of marbling and(or) % IMF with beef flavor have been reported (Gregory et
al., 1994; Riley et al., 2003; Wheeler et al., 2001; 2004; 2005). Genetic relationships between
beef flavor and marbling (or %IMF) suggest that selection of cattle for increased marbling or IMF
would result in gradual improvement of beef flavor.