The American Hereford Association (AHA) recently released tenderness EPDs for sires enrolled in the National Sire Evaluation program. Since 1998, the AHA and other breed associations have been involved in ongoing research through the NCBA Carcass Merit Project. The project set out to quantify the genetics of tenderness in major US beef breeds through collection of data for tenderness EPDs, and through the validation of previously identified genetic markers that influenced tenderness and other carcass traits. The study was funded by the participating breed associations and by the Cattlemen's Beef Board, through the $1 per head beef checkoff.
The results of the investigation of the genetics involved in beef tenderness indicate the tenderness trait is heritable. Therefore, in an effort to provide Hereford breeders adequate data when making sire selection decisions and to assist producers in selecting for this trait, the AHA developed tenderness EPDs from the carcass data in the research project.
Carcass traits are an important tool for sire selection and play a huge role in consumer satisfaction. Dan Moser, Department of Animal Sciences and Industry at Kansas State University (KSU), Manhattan, Kan., says, "While consumers choose beef over competing meats primarily for its distinctive flavor, most objectionable eating experiences are the result of insufficient tenderness. Therefore, genetic improvement of the cattle population for tenderness should result in greater consumer satisfaction with beef, increased consumer expenditures on beef products and ultimately a larger market share."
Tenderness data were collected on total of 1,462 steer progeny of 69 prominent Hereford sires. Those progeny were the result of random matings to commercial Hereford and Hereford-cross cows. After weaning, progeny were fed in commercial feedlots and harvested in commercial packing facilities. Typical carcass data were collected on each animal. Rib steaks from each carcass were shipped to the KSU meats laboratory, where they were aged 14 days and cooked to a medium degree of doneness. Warner-Bratzler shear force (WBSF), a mechanical, repeatable measurement of the force required to shear a core of steak, was measured on eight half inch cores from each steak. The average of the eight core samples was used to calculate EPDs for tenderness (WBSF). Five of the sires from each breed had a second steak retrieved for sensory panel evaluation, where a trained taste panel evaluated each steak for tenderness, juiciness and flavor.
Results show heritability of shear force was low to moderate, in agreement with other studies. Compared with other breeds, the lower heritability of the tenderness trait in Herefords indicates there may be less genetic variation within Herefords than other breeds. The favorable genetic correlation between WBSF and marbling indicates that selection for marbling should improve tenderness in Herefords. The extremely strong, favorable genetic correlation between shear force and taste panel tenderness indicates they are the same trait, whether measured mechanically or by sensory panelists.
Tenderness (WBSF) EPDs for the 69 sires with measured progeny appear in the 2004 Hereford Sire Summary. The accuracy values for most sires are fairly low, due to the limited amount of progeny per sire and the moderately low heritability of WBSF. Still, significant variation exists among the sires, enough that breeders can improve tenderness through selection, if desired.
For more information, including complete EPDs on these Hereford sires, see the April issue of Hereford World. Spring 2004 sire summaries are available from the AHA and can be viewed on-line at www.hereford.org.