Dairy cows grazing on the Northern Southland Plains.br/br/Holstein-Friesian cows are large, and usually black and white. In New Zealand they produce over 4,000 litres of milk per season from a grass-based diet. Historically, there was little distinction between dairy cattle and beef cattle, with the same stock often being used for both meat and milk production. Today, the bovine industry is more specialized and most dairy cattle have been bred to produce large volumes of milk. br/br/Dairy farming is now a major part of the New Zealand economy, becoming an NZ$11 billion industry by 2010, with over 5 million dairy cattle.