Technologies based on DNA analysis with applications in animal production have recently experienced tremendous growth as a result of the progress of genomic research in all livestock species. The most relevant applications are the use of DNA variability for genetic characterization of populations and animal identification, detection of carriers of undesirable allelic variants and marker-assisted selection (MAS). MAS is the application that has raised more expectations among cattlemen. In this case, the information obtained directly from the candidate's DNA would reduce the need for phenotypic information, which in turn would have a direct impact on the rate of genetic progress by increasing accuracy in the estimation of breeding values and decreasing the generation interval. The progressive discovery of genes involved in the regulation of production traits lead to the construction of panels of markers that are validated and rapidly transferred to the industry. This process tends to the implementation of the so-called genomic selection, in which the association with a very high number of markers simultaneously attempts to capture the effect of all the genes with influence on a given trait. In Argentina, there is growing interest on the new technology, which is far from reaching its limit. More applications will be developed in the coming years that will progressively be more cost effective and that undoubtedly will have great impact on production efficiency.

Las tecnologías basadas en el análisis de ADN con aplicación en producción animal han experimentado un enorme desarrollo, como resultado del crecimiento de la investigación en genómica en todas las especies. Las aplicaciones concretas son el aprovechamiento de la variabilidad del ADN para la caracterización de poblaciones y la identificación animal, la detección de portadores de variantes alélicas indeseables y la selección asistida por marcadores. Esta última es la aplicación que más expectativas ha despertado en el sector productivo. En este caso, la información obtenida directamente del ADN del individuo permitiría reducir la necesidad de información fenotípica, lo que a su vez tendría un impacto directo sobre la tasa de progreso genético al aumentar la precisión y disminuir el intervalo generacional. El descubriendo progresivo de cada vez más genes involucrados en variables productivas llevó a la construcción de paneles de marcadores que son validados y rápidamente transferidos al sector productivo. El proceso tiende hacia la denominada selección genómica, en la cual la asociación con un alto número de marcadores intenta capturar simultáneamente el efecto de todos los genes que afectan una variable. En Argentina, el sector ganadero está viendo estos avances con gran expectativa. Se empieza a valorar la efectividad de la tecnología y lentamente crece la demanda de análisis genómicos. La tecnología está lejos de llegar a un techo y en los próximos años surgirán aplicaciones cada vez más efectivas, que sin duda tendrán alto impacto en la eficiencia de producción.

The objective of this paper was to determine the association of a SNP in the µ-calpain gene at position 316 with growth and quality of meat traits of steers grown on pasture. Fifty-nine Brangus and 20 Angus steers were genotyped for CAPN1 316. Warner Bratzler shear force was measured in l. lumborum samples after a 7-day aging period. A multivariate analysis of variance was performed, including shear force (WBSF), final weight (FW), average daily gain (ADG), backfat thickness (BFT), average monthly fat thickness gain (AMFTG), rib-eye area (REA), and beef rib-eye depth (RED) as dependent variables. The CAPN1 316 genotype was statistically significant. Univariate analyses were done with these variables. The marker genotype was statistically significant (p < 0.05) for WBSF (kg: CC: 4.41 ± 0.57; CG: 5.58 ± 0.20; GG: 6.29 ± 0.18), FW (kg: CC: 360.23 ± 14.71; CG: 381.34 ± 5.26; GG: 399.23 ± 4.68), and ADG (kg/d: CC: 0.675 ± 0.046; CG: 0.705 ± 0.016; GG: 0.765 ± 0.014) Shear force, final weight and average daily gain were significantly different according to the CAPN1 316 marker genotypes. The marker genotype was statistically significant in the multivariate analysis (p = 0.001). The first characteristic root explained 89% of the differences among genotypes. WBSF, FW and ADG were the most important traits in the first vector, indicating that animals with the marker genotype for lowest WBSF also have the lowest FW and ADG.

The activity of the calpains/calpastatin proteolytic system is closely related to the postmortem tenderization of meat. We investigated the association between beef tenderness and single nucleotide polymorphism (SNP) markers on the CAPN1 gene (SNP316, alleles C/G; SNP530 alleles A/G) and the CAST gene 3' untranslated region (SNP2870, alleles A/G). We sampled nine slaughter groups comprising 313 steers which had been reared in beef production systems in Argentina between 2002 and 2004 from crosses between Angus, Hereford and Limousin cattle. Minor allele frequencies for the markers were 0.27 to 0.46 (C), 0.02 to 0.18 (A), and 0.24 to 0.53 (A), respectively. The presence of CAPN1 markers had significant effects on meat shear force but no detectable effects were demonstrated for the CAST marker. The shear force of meat from steers with the SNP316 CC genotype was 11% lower than for the SNP316 CG genotype and 17% lower than for the SNP316 GG genotype. There were very few steers with the SNP530 AA genotype and, contrary to previous studies, meat from steers with the SNP530 GG genotype showed an 11.5% higher shear force than that from steers with the SNP530 GA genotype. Final body weight, carcass weight and rib eye area were not affected by any of the markers. These results support the concept that CAPN1 variants are associated with tenderness across a wide range of beef production systems.

The influence of cytoplasmic inheritance on birth and weaning weight was evaluated in an experimental Hereford herd. Data on 1,720 records for birth and weaning weights from calves born between 1963 and 2002 were studied. Variance components were estimated using MTDFREML procedures and an animal model was fitted for each trait. Direct and maternal additive effects and permanent environment and maternal lineage effects were treated as random, while year and month of birth, age of dam and sex of the calf were treated as fixed. Identification of maternal lineages was based on pedigree information. The contribution to phenotypic variance of cytoplasmic lineages defined by pedigree information was negligible for both traits. Mitochondrial genotypes of cows present in the herd in 2002 were analyzed by single strand conformation polymorphism (SSCP) analysis. Only five different genotypes were identified among 23 maternal lineages. All the animals with records were assigned to maternal genotypes based on pedigree information. The statistical analysis was repeated, removing maternal lineage from the model and including mitochondrial genotype as a fixed effect. No evidence of genotype effects was detected. These results suggest a negligible effect of the mitochondrial genome on the preweaning traits of this Hereford herd.