Meat is animal flesh that is used as food. Most often, this means the skeletal muscle and associated fat and other tissues, but it may also describe other edible tissues such as organs and offal. In the Anglosphere, meat is generally used by the meat packing industry in a more restrictive sense—the flesh of mammalian species (pigs, cattle, lambs, etc.) raised and prepared for human consumption, to the exclusion of fish, poultry, and other animals. Usage varies worldwide by culture, and some countries such as India have large populations that avoid the consumption of all or most kinds of meat. Game or bush meat is also generally distinguished from that produced by agriculture.
The consumption of meat has various traditions and rituals associated with it in different cultures such as kosher and halal and its production is generally regulated by state authorities as well. This article is mainly focused on that process from primary production to consumption. Agricultural science has identified several factors bearing on the growth and development of meat in animals.
Genetics
Several economically important traits in meat animals are heritable to some degree (see the table to the right) and can thus be selected for by breeding. In cattle, certain growth features are controlled by recessive genes which have not so far been controlled, complicating breeding. One such trait is dwarfism; another is the doppelender or “double muscling” condition, which causes muscle hypertrophy and thereby increases the animal’s commercial value. Genetic analysis continues to reveal the genetic mechanisms that control numerous aspects of the endocrine system and, through it, meat growth and quality.
Genetic engineering techniques can shorten breeding programmes significantly because they allow for the identification and isolation of genes coding for desired traits, and for the reincorporation of these genes into the animal genome. To enable such manipulation, research is ongoing (as of 2006) to map the entire genome of sheep, cattle and pigs. Some research has already seen commercial application. For instance, a recombinant bacterium has been developed which improves the digestion of grass in the rumen of cattle, and some specific features of muscle fibres have been genetically altered.
Experimental reproductive cloning of commercially important meat animals such as sheep, pig or cattle has been successful. The multiple asexual reproduction of animals bearing desirable traits can thus be anticipated, although this is not yet practical on a commercial scale.
Nutrition
The quality and quantity of usable meat depends on the animal’s plane of nutrition, i.e., whether it is over- or underfed. Scientists disagree, however, about how exactly the plane of nutrition influences carcase composition.
The composition of the diet, especially the amount of protein provided, is also an important factor regulating animal growth. Ruminants, which may digest cellulose, are better adapted to poor-quality diets, but their ruminal microorganisms degrade high-quality protein if supplied in excess.Because producing high-quality protein animal feed is expensive, several techniques are employed or experimented with to ensure maximum utilization of protein. These include the treatment of feed with formalin to protect amino acids during their passage through the rumen, the recycling of manure by feeding it back to cattle mixed with feed concentrates, or the partial conversion of petroleum hydrocarbons to protein through microbial action.
In plant feed, environmental factors influence the availability of crucial nutrients or micronutrients, a lack or excess of which can cause a great many ailments. In Australia, for instance, where the soil contains limited phosphate, cattle are being fed additional phosphate to increase the efficiency of beef production. Also in Australia, cattle and sheep in certain areas were often found losing their appetite and dying in the midst of rich pasture; this was at length found to be a result of cobalt deficiency in the soil. Plant toxins are also a risk to grazing animals; for instance, fluoracetate, found in some African and Australian plants, kills by disrupting the cellular metabolism. Certain man-made pollutants such as methylmercury and some pesticide residues present a particular hazard due to their tendency to bioaccumulate in meat, potentially poisoning consumers.