Pig production in New Zealand is a sideline of dairying, consequently based on small production units scattered over the dairying areas, especially where milk is separated at home. There are a few larger units near cheese and casein factories, either run by the factories or merely supplied with whey. The 1949–50 Census of Farm Production (the most recent figures) shows that almost 88 per cent of the pigs were on dairy farms. Mixed farming, where pig production was more than a sideline, accounted for only 2·2 per cent. Specialised piggeries, including those based on swill as well as dairy by-products, accounted for 6·4 per cent of the pigs. The few others produced were “household” pigs. Though tanker collection of whole milk for cheese or casein manufacture has resulted in entire groups of farmers ceasing pig production, this has been partly balanced by the increased production by suppliers conveniently placed for delivery of whey, by one or more specialised whey-feeding piggery units, and by factory piggeries.