Where the condition is serious, governments impose regulations on import and export, on the movement of stock, quarantine restrictions and the reporting of suspected cases. Vaccines are available against certain diseases, and antibiotics are widely used where appropriate. At one time, antibiotics were routinely added to certain compound foodstuffs to promote growth, but this practice is now frowned on in many countries because of the risk that it may lead to antimicrobial resistance in livestock and in humans.[44]
Governments are concerned with zoonoses, diseases that humans may acquire from animals. Wild animal populations may harbour diseases that can affect domestic animals which may acquire them as a result of insufficient biosecurity. An outbreak of Nipah virus in Malaysia in 1999 was traced back to pigs becoming ill after contact with fruit-eating flying foxes, their faeces and urine. The pigs in turn passed the infection to humans.[45] Avian flu H5N1 is present in wild bird populations and can be carried large distances by migrating birds. This virus is easily transmissible to domestic poultry, and to humans living in close proximity with them. Other infectious diseases affecting wild animals, farm animals and humans include rabies, leptospirosis, brucellosis, tuberculosis and trichinosis.[46]
Range of species
[edit]There is no single universally agreed definition of which species are livestock. Widely agreed types of livestock include cattle for beef and dairy, sheep, goats, pigs, and poultry. Various other species are sometimes considered livestock, such as horses,[47] while poultry birds are sometimes excluded. In some parts of the world, livestock includes species such as buffalo, and the South American camelids, the alpaca and llama.[48][49][50] Some authorities use much broader definitions to include fish in aquaculture, micro-livestock such as rabbits and rodents like guinea pigs, as well as insects from honey bees to crickets raised for human consumption.[51]
Products
[edit]Animals are raised for a wide variety of products, principally meat, wool, milk, and eggs, but also including tallow, isinglass and rennet.[52][53] Animals are also kept for more specialised purposes, such as to produce vaccines[54] and antiserum (containing antibodies) for medical use.[55] Where fodder or other crops are grown alongside animals, manure can serve as a fertiliser, returning minerals and organic matter to the soil in a semi-closed organic system.[56]