Wanganui's only commercial pig farm has limited the time its sows spend in crates and is working toward an anaerobic pond system for treating its effluent.
The change to sow housing should please animal welfare activists and the pond system may create less odour for their many neighbours.
"Pigs are like barking dogs. Nobody wants them next door," co-owner Ross Skilton said.
Aorere Farms is a big operation, with 4500 pigs housed indoors in two locations and eating their way through 50 tonnes of food a week.
It was started by Allan and Doris Skilton and is now run by their sons, Ross and Grant.
It's the keeping of pregnant sows in "sow crates" that has made the most waves in animal welfare circles.
Since December 2012 the Skiltons' sows have been in the crates for only the first month of their pregnancies. This kept them safe from potentially stressful and damaging attacks by other sows.
The rest of the time the sows are penned in groups of three to six, with skilled stockmen judging which will get on together without fighting. Pigs often attack each other when they're housed together, and that can end in injuries and aborted pregnancies.
Under recent welfare code changes the Skiltons will have to stop using sow crates by 2015, which they expect will cost them $200,000. They said the changes to their operation were considerable and made "to meet the demands of the market, which is not necessarily the demands of the animal".
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New Zealand's animal welfare code puts the country's pork in the top 1 per cent in the world, with Switzerland, Finland, the United Kingdom and Sweden. If the Ministry for Primary Industries permits the importation of fresh pork from overseas, New Zealand farmers will have to compete on price with other countries that have much lower standards of animal welfare.
Pig farmers would also risk the introduction of PRRS (porcine reproductive respiratory syndrome), a viral illness that kills 70 per cent of piglets and aborts 15 per cent of sow pregnancies. It doesn't affect human health but is a major headache for producers.
The Skilton farm on the outskirts of Wanganui now has about twice as many neighbours as it did when it intensified production 25 years ago. It deals with its waste, many tonnes of pig excrement a week, by screening it and mixing it with water to irrigate paddocks grazed by cattle.
In the next month it will be moving to a new system which the brothers hope will save them money, treat the waste more fully and prevent odour. They have installed an anaerobic pond to treat waste before it is spray irrigated. The pond will create methane gas that they will use to heat their piggery, and any excess will be flared off, to kill odour.
It's one of just five such ponds in the North Island, and they have high hopes for its success.
About 50 per cent of the world's pork is raised in China, and 10 per cent in the United States. All fresh pork sold here is raised in this country, while 90 per cent of ham and bacon is imported.