Carcass Merit Study Provides Valuable Info for Beef Breeds

A five-year checkoff-funded research project focused on genetics and the identification of carcass merit traits has provided valuable data which various beef breeds and eventually all commercial cattle can use to help improve tenderness and other quality traits of beef.  However, researchers caution that much work remains to be done in this area.

 The study, Genetics of Carcass Merit: Development of EPDs and Genetic Marker Validation, had two primary objectives: Collect data for the development of carcass merit EPDs (expected progeny difference), including tenderness; and attempt to validate previously discovered  Quantitative Trait Loci (QTL) for carcass merit in the U.S. cattle population.  In addition to these objectives, several other benefits were gained from the project.  All have the potential of favorably impacting the beef industry for years to come.

 Researchers collected carcass and shear force data on 8,500 animals, sired by more than 300 different bulls of 14 major U.S. beef breeds.  Of those, DNA samples were collected on nearly 3,700 progeny of 119 sires.  Seventy-one DNA bulls generated enough progeny for a marker analysis. 

 Average shear values for sires within breeds ranged from 1.90 to 6.62 pounds, indicating every breed has significant variation in tenderness, and opportunity to improve.  While Warner-Bratzler shear force was strongly correlated with trained sensory panel tenderness scores, the relationship between shear force and marbling score was weak at best.  These results indicate that Warner-Bratzler shear force is an excellent predictor of consumer experience for tenderness, and that selection for marbling alone will not significantly improve tenderness. 

 Heritability estimates for shear force varied across breeds, but were moderate or higher in some breeds, consistent with other studies.  If researchers can collect adequate amounts of phenotypic shear force data, significant improvement in tenderness is possible through selection. 

 Further analysis of the marker data across sires within breed further validates that at least some of the previous QTL are having significant effects, and are good candidates both for marker-assisted selection and for further study.  QTL is the region on the chromosome where the trait gene is believed to be. 

 The economic portion of the project also revealed useful findings.  Improvement of tenderness has the potential to increase market price, quantity and revenue of fresh beef sales.  Improvement of tenderness both increases the value of beef and stimulates greater demand leading to higher consumer expenditures.  A 10 percent improvement in tenderness would result in approximately a one percent improvement in industry revenue, although the cost of such an improvement is unknown.

 Cooperators on the checkoff-funded project, coordinated for the Cattlemen’s Beef Board and state beef councils by the NCBA, were four universities, the USDA Agricultural Research Service and 14 breed associations.  The breed associations have generated individual databases that will allow the development of EPDs for the carcass traits, including Warner-Bratzler shear force and sensory attributes.