MEAT TENDERNESS GENETIC AND GENOMIC VARIATION SOURCES IN COMMERCIAL BEEF CATTLE MARÍA SALUD RUBIO LOZANO 1 , SELENE ALFARO-ZAVALA 1 , ANA MARÍA SIFUENTES-RINCÓN 2 , GASPAR MANUEL PARRA-BRACAMONTE 2,7 , DIEGO BRAÑA VARELA 3 , RUBÉN DANILO MÉNDEZ MEDINA 1 , CRISTINA PÉREZ LINARES 4 , FRANCISCO RÍOS RINCÓN 5 , ARMIDA SÁNCHEZ ESCALANTE 6 , GASTÓN TORRESCANO URRUTIA 6 and FERNANDO FIGUEROA SAAVEDRA 4 1 Facultad Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, México, DF, Mexico 2 Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Boulevard del Maestro, SN, Esq. Elías Piña, Col. Narciso Mendoza, Reynosa, Tamaulipas 88710, Mexico 3 Agrícolas y Pecuarias-Fisiología, Instituto Nacional de Investigaciones Forestales, Colón, Querétaro, Mexico 4 Instituto de Investigaciones en Ciencias Veterinarias, Universidad Autónoma de Baja California, Mexicali, Baja California, Mexico 5 Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Sinaloa, Culiacán, Sinaloa, Mexico 6 Centro de Investigación en Alimentación y Desarrollo, Hermosillo, Sonora, Mexico 7 Corresponding author. TEL: 87709, 87743; FAX: +528999243627 ext. 87746; EMAIL: gparra@ipn.mx Received for Publication November 4, 2014 Accepted for Publication August 6, 2015 10.1111/jfq.12185 ABSTRACT To assess genetic group (GGR; Bos indicus [Bi], Bos taurus [Bt] and crosses [BtxBi]) and to confirm the calpain (CAPN316 and CAPN4751) and calpastatin (CAST-T1) single nucleotide polymorphism (SNP) effects on Warner–Bratzler shear force (WBSF), 196 animals under commercial conditions were analyzed. A model was fitted including the effect of GGR and considering residuals as adjusted WBSF (aWBSF). Another model was fitted to evaluate the SNP effect on aWBSF. Allele substitution effect (α) and combined favorable alleles in CAPN and CAST on aWBSF were evaluated. GGR showed a significant effect (P < 0.0001) on WBSF; Bt and BtxBi had the lower WBSF. CAPN316 showed significant effect on aWBSF with an α =−0.549 kg. The combined effect of CAPN and CAST showed significant (P < 0.0056) reduction on aWBSF of 0.239 kg by favorable allele. The results remarked the importance of GGR and confirmed CAPN316 and combined effect of CAPN and CAST on prediction of meat tenderness. PRACTICAL APPLICATIONS Knowledge of main factors related to tenderness, as a key related factor to beef consumer satisfaction, would serve as a resource for commercial beef classification and management under slaughterhouse conditions. Confirmation on combined marker effects provides strong validation for marker-assisted management use of these technologies under industry conditions. Additionally, the presented results may be used as a reference for research in the beef industry aimed to provide improvement on beef tenderness to the final product. INTRODUCTION Beef quality is one of the main concerns in the bovine industry and, depending on the regional and country con- ditions, has many definitions (Hocquette and Gigli 2005). Yet, the most important concern is related to consumer satisfaction. Flavor, juiciness and, most importantly, ten- derness are the main traits related to beef quality and con- sumer preference (Mintert et al. 2000). In order to consistently produce quality meat products, the industry must have a clear understanding of the factors affecting meat quality variation (Warner et al. 2010). These factors may include environmental and genetic compo- nents. However, revealing the influence of these factors is a very difficult task to achieve mostly because of the complex- ity of beef quality traits, which are expensive and only pos- sible to measure after slaughter (Gao et al. 2007; Van Eenennaam 2010). In addition, most of these traits have Journal of Food Quality ISSN 1745-4557 1 Journal of Food Quality •• (2015) ••–•• © 2015 Wiley Periodicals, Inc. 150 Journal of Food Quality 39 (2016) 150–156 V C 2015 Wiley Periodicals, Inc. Journal of Food Quality ISSN 1745-4557