What started as a hobby has become part of Kelso dairy farmers Jayne and Phillip Corlett's business strategy.
In addition to milking 600 cows on their 200ha Ardmore Farm Trust property, they diversified to take on pigs and East Friesian sheep as additional income streams.
Mrs Corlett originally bought two Large White pigs to use up extra milk in about 2004, then bought two Berkshire sows after seeing an article about them needing a home.
She later added a recorded boar, then Landrace sows.
Now she usually carries three pedigree Rata Glen Stud boars and 14 pedigree Berkshire, Landrace and Large White sows.
Each sow produces about a dozen piglets, which are then on-sold as weaners at about 7 weeks, and at about 10kg.
In addition to the pigs, she has a small flock of East Friesian sheep, with their offspring sold either to the works or as milking ewes.
Each sow has two litters a year, averaging 14 piglets, which is 280 to 300 piglets a year.
As the sows get older, the number in their litters falls and then they are sent to Timaru to be killed and processed.
''I keep my pigs until about 6 or 7 years old, then their litter sizes tend to fall,'' she said.
''An economic number in a litter is about eight.
''One of girls that I am a bit sentimental about is called Mother and she is about 9.
''The sows are free-range, but go into the shed when they are ready to farrow and they stay there for six weeks, until the piglets are weaned.''
The farrowing pigs can easily move around, and the piglets are allowed to run outside.
''I had one sow, which had 26 piglets, and no way was she going to rear them so I had to take half off her to hand rear.
''We do not dock their tails and do not use farrowing crates.
''We get audited by MPI every year.''
The pigs are born with teeth and as they tend to fight and bite, she sometimes nips the top of the eye teeth off, for the mum's sake.
The shed is cleaned out every day and the effluent stored in a tank before being sprayed on to paddocks.
The pigs eat crushed barley and milk as well as graze outside.
Mrs Corlett said full-grown, the sows and boars could be up to 300kg, and have to be respected, but they do cull the grumpy ones.
''They are just about as intelligent as dogs.''
She said she had pigs that open shut gates, lift the gates off the hinges, and go for walks.
She is president of the New Zealand Pig Breeders Association and the South Island councillor.