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item Casas, Eduardo

Submitted to: Archivos Latinoamericanos De Produccion Animal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2001
Publication Date: 1/2/2002
Citation: Casas, E. 2002. Identification of quantitative trait loci in beef cattle. Archivos Latinoamericanos De Produccion Animal. 10(1):54-61

Interpretive Summary: The objective of this review is to describe the quantitative trait loci (QTL) detected in beef cattle for growth, carcass, and meat quality traits in families developed at the U.S. Meat Animal Research Center (MARC). Regions on eleven different chromosomes have been identified to harbor a gene or group of genes, that affects the performance of an animal. These QTL need to be validated in outbred populations. Populations developed at MARC are found to be suitable to pursue this objective. To validate the QTL in these populations it is necessary to develop novel marker systems that will allow high throughput genotyping. A project to develop these markers has been established at MARC. The purpose is to use genomic information in either functional genomics studies or in marker assisted selection to improve the efficiency in animal breeding schemes.

Technical Abstract: The objective of this review is to describe the quantitative trait loci (QTL) identified in beef cattle at the U. S. Meat Animal Research Center (MARC). Four large half-sib families were developed (two families with 500 offspring each, and two families with an average of 227 offspring) to detect QTL for growth, carcass composition and meat quality traits. Scans in these families, using molecular markers obtained from the bovine linkage map, were done. Regions on chromosomes 2, 3, 4, 5, 6, 8, 13, 15, 16, 27, and 29, were detected to harbor genes associated with these traits. Characterization of the variation of the QTL needs to be assessed in outbred populations. Animals from the Germplasm Evaluation Project, developed at MARC, are suitable populations in which this can be accomplished. New marker systems able to be used in high-throughput genotyping systems need to be developed to characterize the QTL variation in outbred populations. A genomic program is being developed at MARC to produce single nucleotide polymorphisms (SNP) from expressed sequence tags (EST). These molecular markers will provide the means to characterize variation of previously identified QTL. The purpose is to use genomic information to either, identify the alleles of a gene that is producing differences in expression of a trait (Functional genomics), or to use this information in selection schemes supported by marker information (Marker-assisted selection).