<P> 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, 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 . Some authorities use much broader definitions to include fish in aquaculture, micro-livestock such as rabbits and guinea pigs, as well as insects from honey bees to crickets raised for human consumption . </P> <P> Animals are raised for a wide variety of products, principally meat, wool, milk, and eggs, but also including tallow, isinglass and rennet . Animals are also kept for more specialised purposes, such as to produce vaccines and antiserum (containing antibodies) for medical use . 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 . </P> <P> Although all mammals produce milk to nourish their young, the cow is predominantly used throughout the world to produce milk and milk products for human consumption . Other animals used to a lesser extent for this purpose include sheep, goats, camels, buffaloes, yaks, reindeer, horses and donkeys . </P> <P> All these animals have been domesticated over the centuries, being bred for such desirable characteristics as fecundity, productivity, docility and the ability to thrive under the prevailing conditions . Whereas in the past, cattle had multiple functions, modern dairy cow breeding has resulted in specialised Holstein Friesian - type animals that produce large quantities of milk economically . Artificial insemination is widely available to allow farmers to select for the particular traits that suit their circumstances . </P>

Information about how floods affect agriculture and animal husbandry