Other farmers in the region are attempting to breed pigs of around 200kg but one, Zhao Hailin, said the aim was to raise them "as big as possible".
Farmers create giant pigs by selectively breeding those that grow fastest, then feeding them a high-energy, high-protein diet, typically of soya and wheat, to fatten them up.
The pigs being bred in Guangxi sell for up to 10,000 yuan ($2200), more than three times the average monthly disposable income in the region's capital, Nanning, according to Bloomberg News. But animal welfare campaigners have expressed concerns about the pressure on a pig's heart, lungs and legs from super-sizing them.
Peter Stevenson, of Compassion in World Farming, said: 'The largest pigs in Europe, bred for Parma ham, are 350lb and the average is 175lb to 220lb, so the size of these Chinese pigs is appalling.
"The pigs are being bred to three times the top size I have ever heard of and that could be extremely painful for the animals. We know when broiler chickens are bred to grow very fast and big like this that it creates a build-up of fluid in the abdomen because their heart cannot support their body size."
He added: "This is also likely to lead to respiratory problems, with the pigs' hips and legs likely to suffer problems from supporting that amount of weight. If it happened here, it would be likely to contravene animal cruelty laws."
With the pork shortage in China pushing up prices, famers across the country are trying to boost the size of their animals.
A manager at one of China's top pig farms said: "For us, the cost of raising pigs is about 10 yuan ($2.20) per kilo, while the pork prices are at 30 ($6.60) in some places. Every kilo more meat you get means double profits. Everyone wants to raise fatter pigs."
More than a million pigs in China have been killed by African swine fever, which hit the country a year ago and has devastated farming.
China produces around half of the world's pigs and pork accounts for more than 60 per cent of Chinese families' meat consumption.
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In August, pig stocks dropped nearly 40 per cent from a year earlier, according to the Ministry of Agriculture and Rural Affairs.
Chinese vice-premier Hu Chunhua said the pork shortage would be 'extremely severe' into the first half of next year.
He urged farmers to resume normal production but many are nervous after having their herds devastated by swine flu.