Genetic Control of Meat Quality Traits

Meat was originally produced from non-specialized animals that were used for a variety of purposes, in addition to being a source of food. However, selective breeding has resulted in “improved” breeds of cattle that are now used to produce either milk or beef, and specialized chicken lines that produce eggs or meat. These improved breeds are very productive under appropriate management systems. The selection methods used to create these specialized breeds were based on easily measured phenotypic variations, such as growth rate or physical size. Improvement in the desired trait was achieved by breeding directly from animals displaying the desired phenotype. However, more recently sophisticated genetic models have been developed using statistical approaches that consider phenotypic information collected, not only from individual animals but also from their parents, sibs, and progeny. This combined information allows the genetic potential of individuals to be the better predicted. The predicted potential for several traits can then be combined into an index which provides a measure of the overall genetic merit of the individual. Using these statistical approaches animals are selected for breeding using the index of their estimated breeding value (EBV), rather than directly on their phenotype. The results of these phenotype focused selection approaches have been highly successful, with dramatic improvements in the traits under selection. Modern broiler chickens used for meat production are eight times larger and grow much more rapidly than layer types that have been selected for egg production. Specialized beef cattle grow rapidly reaching a mature size in less than a year compared with the 24–36 months required to “finish” traditional breeds. Milk production from specialized dairy cows has also increased dramatically over the past 20 years under selection. However, these past selection choices have resulted in new problems,