Some twenty breeds of cattle are now commonly kept in the British Isles and these are classified into three types; beef, dairy and dual-purpose cattle.
Despite the broad classification of cattle into beef, dairy and dual-purpose, farmers are constantly striving to produce higher-yielding stock, often by cross-breeding.
Dairy calves are usually taken from their mothers at or a few days after birth and reared artificially as the cow's milk is of primary importance to the dairy farmer (beef cows are not normally milked and the calves are left to suckle as long as possible). The avarage yield from a dairy cow is about 4,530 litres (822 gallons) per year though this varies from the small Dexter which produces 2,200-3,300 litres (400-600 gallons) per year to the Friesian which often gives 11,000 litres (2,000 gallons) per year.
