RESUMO
We examined allele and genotype frequencies for the molecular markers CAPN1 316, CAPN1 4751 and TG5, and determined whether they are associated with beef quality traits in Mexican cattle. One hundred and twenty-four longissimus dorsi muscle samples were collected from cattle from north, central and southern Mexico. CAPN1 316 and CAPN1 4751 frequencies were determined using the allelic discrimination assay and the TG5 marker was typed by PCR-RFLP. Meat quality traits included intramuscular fat content (IMF) and tenderness determined by Warner-Bratzler shear force (WBSF) at 24 h postmortem. The association test was made using a mixed model, including genotypes, genetic group, and sampling location as fixed effects. Least squares means and significant interactions were compared using least significant differences based on the mixed procedure. CAPN1 316 CC was found at a low frequency (0.03) and has been reported as a favorable genotype associated with tenderness meat. Genotype frequencies for CAPN1 4751 were similar in favorable (CC) and unfavorable (TT) genotypes (0.26 and 0.28, respectively). The TG5 CC genotype had a frequency of 0.73, while the TT genotype frequency was 0.01. The means for WBSF and IMF were 4.08 ± 1.35 kg and 5.23 ± 2.14%, respectively. Sampling site and the CAPN1 316 genotypes significantly affected WBSF (P < 0.05). Samples collected from Hermosillo, Sonora, had the lowest WBSF (P < 0.05), while those collected in Veracruz were toughest (WBSF = 5.267 kg). The effect of GG and TG5 genotypes on IMF was significant (P < 0.05). CAPN1 316 and TG5 markers were found to be significantly associated with beef quality traits and thus will be useful for Mexican beef characterization.
Assuntos
Marcadores Genéticos , Produtos da Carne , Animais , Sequência de Bases , Bovinos , Primers do DNA , Frequência do Gene , Genótipo , MéxicoRESUMO
The purpose of this study was to compare the chemical composition and sensory characteristics of two beef muscles (semimembranosus, SM and adductor, AD) from the inside round of Mexican and US origins. Inside rounds were obtained from 20 Mexican bull carcasses, representing beef of Mexican origin. Forty-vacuum packaged USDA Choice and Select inside rounds were purchased from a local trader, representing US beef. Muscles were analyzed for chemical composition, Warner-Bratzler shear force (WBSF), cooking loss percentage, instrumental color, textural profile, and consumer acceptability. Muscles imported from the US contained more intramuscular fat, had higher cooking loss percentages, lower shear force values, and higher consumer ratings for overall desirability than Mexican counterparts (P<0.05). Choice and Select beef samples had similar WBSF values (P>0.05). Consumers found differences in juiciness and tenderness ratings between the two muscles, with the SM being tougher and less juicy than the AD (P<0.05).