- Meat quality is an important production trait in cattle, sheep, pigs, poultry, and other meat-producing animals. It influences consumer acceptance, nutritional value, processing characteristics, product consistency, and economic returns. The genetics of meat quality examines how inherited differences affect characteristics such as tenderness, colour, juiciness, flavour, intramuscular fat, water-holding capacity, and carcass composition. Genetic improvement of these traits helps breeding programs produce meat that meets market requirements while maintaining animal health, welfare, and production efficiency.
- Meat quality is a complex, polygenic trait, meaning that many genes contribute to its expression. Genetic variation affects muscle development, muscle fibre characteristics, fat deposition, connective tissue, energy metabolism, and the biochemical processes that occur after slaughter. However, meat quality is also influenced by nutrition, age, sex, handling, transport, slaughter conditions, chilling, ageing, and storage. Reliable genetic evaluation must therefore distinguish inherited differences from environmental and processing effects.
- Meat tenderness is one of the most important quality characteristics because it strongly influences eating satisfaction. Genetic differences can affect muscle structure, connective tissue properties, and the activity of enzymes involved in post-mortem protein breakdown. In cattle, the calpain–calpastatin system, which includes the proteins encoded by CAPN1 and CAST, has been widely studied for its association with meat tenderness. The effects of genetic variants depend on the population and production system, and tenderness also depends on post-mortem handling and ageing.
- Intramuscular fat, commonly called marbling, refers to fat deposited within muscle tissue. It contributes to flavour, juiciness, and tenderness in some meat products and is an important selection trait in several beef production systems. Genes influencing lipid metabolism, fat-cell development, and nutrient partitioning contribute to variation in marbling. Nevertheless, greater intramuscular fat is not always the best objective because market preferences, carcass yield, feed costs, and the desired fat composition differ across production systems.
- Meat colour is another important trait because consumers often use colour as an indicator of freshness and acceptability. It is influenced by myoglobin concentration, muscle metabolism, animal age, species, oxygen exposure, and storage conditions. Genetic differences can affect muscle fibre type and metabolic characteristics, but colour should be evaluated under standardized conditions. Water-holding capacity is also important because it affects drip loss, cooking loss, juiciness, and processing yield. Genetic factors contribute to muscle metabolism and protein changes that influence how much water meat retains.
- Meat pH is a key indicator of post-mortem muscle metabolism. After slaughter, stored muscle glycogen is converted into lactic acid, causing pH to decline. The rate and extent of this decline influence colour, water-holding capacity, tenderness, and shelf life. Genetic differences in muscle energy metabolism can affect these processes, but stress, handling, transport, and slaughter conditions are also major influences. In pigs, for example, genetic variants affecting muscle metabolism have been associated with quality defects such as pale, soft, exudative meat, while other combinations of genetics and pre-slaughter conditions can contribute to dark, firm, dry meat in several species.
- Heritability of meat quality traits describes the proportion of observed variation within a particular population and environment that is attributable to genetic differences. Heritability varies among traits, species, breeds, and measurement methods. Some carcass and composition traits can be evaluated using routine records, whereas direct measurements of tenderness, flavour, and other eating-quality characteristics may be more expensive or difficult to obtain. Reliable data collection and appropriate adjustment for age, sex, diet, slaughter conditions, and other systematic effects are essential for accurate genetic evaluation.
- Breeding values for meat quality estimate an animal’s genetic merit and its expected ability to transmit relevant traits to its offspring. These estimates can incorporate individual records, information from relatives, progeny data, and genomic information. Genomic selection can improve the identification of breeding animals with desirable meat-quality characteristics, especially when genomic predictions are supported by sufficiently large and representative reference populations. Genetic testing for specific variants may also provide useful information, but individual markers should not replace comprehensive genetic evaluation.
- Meat quality must be considered alongside carcass traits, including carcass weight, dressing percentage, muscle yield, fatness, and the distribution of valuable cuts. Genetic relationships between meat quality and carcass composition can create trade-offs. For example, selection for lean meat yield may affect fat deposition, while selection for rapid growth may influence muscle characteristics or the time required to reach market weight. The direction and strength of these relationships depend on the species, population, and traits measured.
- Modern breeding programs use selection indexes to combine meat quality with growth rate, feed efficiency, fertility, health, survival, and other economically important traits. Genetic correlations help breeders predict how selection for one trait may influence others. Balanced breeding objectives are essential because improving tenderness or marbling alone may not maximize profitability or sustainability if feed costs, reproductive performance, animal welfare, and carcass value are ignored.
- The long-term goal of genetic improvement is to produce animals that deliver consistent, high-quality meat efficiently while maintaining health, welfare, and environmental sustainability. By combining standardized meat-quality measurements, reliable performance recording, breeding values, genomic technologies, and balanced selection objectives, animal breeding programs can improve tenderness, marbling, colour, water-holding capacity, and overall product quality across generations.
