GeneSTAR^® Tenderness is a DNA genetic marker panel test comprised of three markers (CAST-T1, Calpain 316-T2, and Calpain 4751-T3). An increase in “tenderness” is associated with substituting a “T” allele at Calpastatin (CAST-T1), a “C” allele at Calpain 316-T2 and a “C” allele at Calpain 4751-T3. The following table shows the decrease in “toughness” (Warner-Bratzler Shear Force, lb) for each of the possible genotypes contrasted to the least tender genotype (i.e.  a “0” star animal; CAST-T1 “CC”, Calpain 316-T2 “GG”, and Calpain 4751-T3 “TT”) calculated from a combined analysis of 1458 cattle from four sample populations (Charolais x Angus cross, Hereford and two purebred Brahman) used in the validation study.   

The Calpastatin marker (CAST-T1) and the Calpain T2-T3 haplotype (CAPN1 316 and CAPN1 4751) were each highly significant. Each calpastatin “T” was associated with a decrease of 0.3 lb of Warner-Bratzler Shear Force, and substituting the Calpain T2-T3 “C-C” haplotype for the Calpain T2-T3 “G-T”  haplotype was associated with a decrease of 0.8 lb of Warner-Bratzler Shear Force.  Among genotypes with sufficient information there was a 2.2 lb. difference in WBSF between the most tender (“six star”) and the least tender (“zero star”) genotype. Breeders should not expect gains this large because no herd will consist 100% of the ‘least tender’ genotype.