35 Applying GGP-F250 genotypes to elucidate the biochemical basis for animal variation in meat quality attributes

Abstract

Understanding the biological factors regulating animal variation in meat quality traits continues to challenge meat scientists. Meat scientists have studied the impacts of numerous intrinsic and extrinsic variables on meat quality traits. Often, component traits, known to directly contribute to the trait of interest, have been utilized to determine the mechanisms by which these impacts are made. However, only a limited amount of the variation in these traits is explained by component traits, indicating that a significant knowledge gap exists. The rise of genotyping assays for functional alleles provides an opportunity to further understanding of the biological basis of meat quality traits. For example, lean color is the primary factor utilized by consumers in making purchasing decisions. Cuts from some carcasses discolor rapidly and must be discounted or discarded. Component traits (reducing ability and oxygen consumption) generally explains a total 30 to 40% of the variation in lean color stability. A genome-wide association study (GWAS) was conducted using GGP-F250 genotypes from 2,476 steers representing crosses of 18 beef breeds that had been phenotyped for lean color change during simulated retail display. The GWAS identified 417 single nucleotide polymorphisms (SNP) explaining the heritable variation (0.45). Identified genes included genes coding for reductases and cytochromes as well as mitochondrial genes, which are consistent with conventional wisdom regarding lean color stability. However, other genes identified are related to muscle contraction, action potential mediation, calcium binding, actin binding, stress response, and apotosis. In addition, gene ontology analysis indicates 128 genes contributing to metabolic processes, with 74 being associated with nucleobase containing compound metabolic processes. Thus, these results suggest novel mechanisms, which have not been previously studied in detail in relation to lean color stability. This approach provides a means to increase understanding of the biological regulation of meat quality traits.