Quantitative and molecular genetic influences on properties of beef: a review

Abstract

Abstract. The scientific literature is reviewed to identify quantitative and molecular genetic influences on quantity and quality of beef. Genetic variation between breeds is of similar magnitude to genetic variation within breeds for many economically important traits. Differences between breeds are significant and large for most carcass and beef quality attributes, including beef tenderness, although differences for sensory juiciness and flavour are of little practical importance. For traits such as beef tenderness, between-breed differences may be more easily exploited than within-breed differences, because exceptional breeds are easier to identify than exceptional animals. Effects of heterosis on carcass and beef quality attributes are relatively small (3% or less), with most effects mediated through heterotic effects on weight. Carcass composition traits (e.g. carcass weight, fat thickness and marbling) are moderately to highly heritable. Most estimates of retail beef yield percentage are highly heritable, offering good potential for within-breed selection for the trait, although a moderate to strong antagonistic relationship exists between yield and marbling. This relationship needs to be considered in within-breed selection programs for yield percentage. Early estimates of heritability of objective measures of beef tenderness (Warner Bratzler shear force values) indicated tenderness was moderately to highly heritable. Recent estimates using larger numbers of carcasses and more discriminatory methods of analysis indicate that beef tenderness is lowly heritable in Bos taurus breeds and moderately heritable in Bos indicus and Bos indicus-derived breeds. Within breeds, measures of 24-h calpastatin activity are genetically strongly correlated with shear force values but are more heritable. However, phenotypic correlations between shear force values and 24-h calpastatin activities are low. There are also inconsistencies in relationships between these measurements across breeds. Low correlations between tenderness in different muscles, low to moderate heritabilities and inconsistent variation within-and between-breeds for traits such as 24-h calpastatin activity suggest that genetic improvement in beef tenderness may be difficult. The possibility exists that significant mitochondrial genetic effects occur for some carcass and beef quality attributes. A major gene for muscular hypertrophy in cattle significantly affects carcass and beef quality characteristics. Genome-wide screening of DNA markers indicates a number of putative Quantitative Trait Loci (QTL) associated with carcass and meat quality characteristics. Published data for these QTL are summarised. Strategies to combine quantitative and molecular genetic information to maximise genetic progress are discussed.

Effect of postweaning growth and bulls selected for extremes in retail beef yield and intramuscular fat on progeny liveweight and carcass traits

“…Published heritability estimates for yield ranged from moderate (0.39) to high (0.73); Wheeler et al (1996), Burrow et al (2001) and Reverter et al (2003). Thus, the differences in the yield of the progeny from the Angus sire types were to be expected, and indicate the changes that can be made through appropriate sire selection.…”

Opportunities for predicting and manipulating beef quality

“…This area is commercially strategic and many DNA genotyping methods for specific genes have been already patented (reviewed by Hocquette et al, 2007a). Genetic research programs have been developed in several countries for detecting QTL of beef and meat quality traits (Burrow, Moore, Johnston, Barendse & Bindon, 2001, Burrow, 2008. However, the association between the detected QTL and the target traits appeared to be different according to breed.…”

Regrouping unfamiliar animals in the weeks prior to slaughter has few effects on physiology and meat quality in Bos taurus feedlot steers

“…The term breed in this analysis encapsulates not only genetics of the two lines but also the effects associated with property of origin, and pre-feedlot entry management. Flight time is a measure of temperament of cattle that has been found to be genetically correlated with growth rate (Burrow et al 2001;Petherick et al 2002) and genetically (Reverter et al 2003) and phenotypically (Voisinet et al 1997;Petherick et al 2002) correlated with meat quality in Bos indicus derived breeds. In addition, B. indicus and B. indicus cross cattle with short flight times tended to lose more weight during long distance road transport and recover weight more slowly in the month following transport than animals with slow flight times (H. M. Burrow and I. G. Colditz, unpubl.…”