PIG number 5422 saunters into the pen, circles its few square metres and mounts a plastic stand. The farmer cleans the animal’s underside, feels around and draws out what appears to be a thin pink tube around 30cm long. He begins to massage. Pigs elsewhere snort, grunt or squeal, but the alpha pig is unmoved. Soon he has filled a thermal cup with more than 60 billion sperm. Around 150 pigs will owe their short, brutish lives to this emission.

A malty smell hangs in the air at the Fuxin Breeding Farm in Jiangxi province in central China, 10 hectares of low concrete barns and fields beside a small reservoir, which is home to around 2,000 pigs. The business was started four years ago by 31-year-old Ouyang Kuanxue. Mr Ouyang’s friends say he was destined to be a pig farmer—he was born in the Chinese zodiacal year of the pig—but his own explanation is more prosaic: when he came back to Pingxiang, his hometown, in 2003 after studying management at university in Beijing, he could not think what else to do. His grandfather was a coalminer who kept a few pigs. His father already had 100. He decided to expand.

Now the whole family is involved: together they have three farms with a total of around 5,000 swine. Mr Ouyang’s younger brother is in charge of production; his sister-in-law runs the office. The past year has been hard for them and other pig farmers, Mr Ouyang says, because pork prices have been low and feed expensive. But this lean year followed many fat ones. Mr Ouyang drives a Volkswagen SUV; his wife has a new Audi, wears a Cartier bracelet and runs two nail bars; they own an apartment in a new block in the local town. Mr Ouyang has a panoply of pig-related news feeds on his phone. Still, when he goes out for dinner with friends, he tends to avoid pork.

A brief history of Chinese pork

The family’s good fortune is emblematic of China’s flying pig market over the past 35 years. Since the late 1970s, when the government liberalised agriculture, pork consumption has increased nearly sevenfold in China. It now produces and consumes almost 500m swine a year, half of all the pigs in the world. The tale of Chinese pigs is thus a parable of the country’s breakneck economic rise. But it is more than symbolic: China’s lust for pork has serious consequences for the country’s economy and environment—and for the world.

Pigs have been at the centre of Chinese culture, cuisine and family life for thousands of years. Pork is the country’s essential meat. In Mandarin the word for “meat” and “pork” are the same. The character for “family” is a pig under a roof. The pig is one of the 12 signs of the Chinese zodiac: those born in that year are said to be diligent, sympathetic and generous. Pigs signify prosperity, fertility and virility. Poems, stories and songs celebrate them. Miniature clay pigs have been found in graves from the Han Dynasty (206BC-220AD). Historians think people in southern China were the first in the world to domesticate wild boars, 10,000 years ago.

For centuries sacrificial pigs—and the eating of pork—featured prominently in all forms of commemoration and festivity. At the autumnal Double Ninth Festival (on the ninth day of the ninth lunar month), male elders gathered at their ancestors’ tombs and slaughtered a pig as a symbol of that forebear’s ongoing provision for his descendants. When an estate was in financial trouble, pigs were the last expense to go, says James Watson, an anthropologist at Harvard University, because if the autumn rites were neglected, the ancestor would die a second, terrible death, a final expiration of his spirit.

Every household needs one Almost every rural home once had a pig, not least because, well into the Communist era, the animals were part of the household recycling system. They consumed otherwise inedible waste and were valued for their manure (even Mao Zedong was a fan of the “fertiliser factory on four legs”). And their meat has always been central to Chinese cooking: it has “the perfect flavour for Chinese cuisine,” reckons Fuchsia Dunlop, a food writer and cook. Nothing is wasted. Pigs’ faces are served whole as a gourmet treat; their brains, says Ms Dunlop, are “soft as custard, and dangerously rich”. The appeal is medicinal as well as culinary: the innards are ascribed therapeutic benefits. From trotter to tail, the Chinese eat the whole hog. Still, for much of China’s history, pigs were a luxury consumed only rarely, sometimes extremely rarely. That has changed dramatically.

Everything but the squeal

Lei Xiaoping, the manager of Mr Ouyang’s farm, eats pork for every lunch and dinner these days—swine from the farm that have died in a fight or are too small to sell. He is not squeamish about guzzling pigs he has reared himself. After all, as a child Mr Lei (now aged 51) ate pork only three times a year.

Even before the revolution of 1949, most people in China got only 3% of their annual calorific intake from meat. Pork soon became scarcer still. Tens of millions died in the famine that followed Mao’s Great Leap Forward in the late 1950s and early 1960s. For decades after that peasants would rub pork fat around their woks to give their vegetables a meaty hint, says Ms Dunlop, before putting the fat away to use on another occasion. As recently as the early 1990s many Chinese mostly subsisted on a diet of vegetables bought at street markets.

For Mr Lei, as for many of his countrymen, the years of deprivation are well within living memory. Not surprising, then, that eating meat has become a symbol of triumph over hardship, as much a part of China’s transformation as the towering skyscrapers and glistening cities. Grandparents who once went hungry stuff their grandchildren with the treats they lacked—and top of the list is pork. The average Chinese now eats 39kg of pork a year (roughly a third of a pig), more even than Americans (who typically prefer beef), and five times more per person than they ate in 1979.

Four legs good The most obvious impact has been on the pigs themselves. Until the 1980s farms as large as Mr Ouyang’s were unknown: 95% of Chinese pigs came from smallholdings with fewer than five animals. Today just 20% come from these backyard farms, says Mindi Schneider of the International Institute of Social Studies in The Hague. Some industrial facilities, often owned by the state or by multinationals, produce as many as 100,000 swine a year. These are born and live for ever on slatted metal beds; most never see direct sunlight; very few ever get to breed. The pigs themselves have changed physically, too. Three foreign breeds now account for 95% of them; to preserve its own kinds, China has a national gene bank (basically a giant freezer of pig semen) and a network of indigenous-pig menageries. Nevertheless, scores of ancient variants may soon die out. But China’s pigs are far from the only victims of their popularity. Demand for them worries the Communist Party, underpins what will soon be the world’s biggest economy and threatens Amazon rainforests.

This little piggy stayed home

The Chinese eat so much pork that when its price goes up, the cost of other things rises, too. For the Communist Party, therefore, keeping affordable meat on the table is vital, not least for the stability of the economy. In 2007, for example, an estimated 45m pigs died in China from “blue ear pig disease”. Pork prices rocketed; the annual rate of increase of the consumer price index (sometimes known as the “consumer pig index” because of the creature’s prominent role in it) hit a ten-year high. Panic buying ensued. There were reports of customers being injured in a crush on a supermarket escalator when rushing to buy cheap chilled pork in Guangzhou, and a general pork-buying frenzy across China. Imports doubled.

In response the party established the world’s first pork reserve, some of it in frozen form and some the live, snorting variety. This aims to keep pork affordable and reasonably priced: when pigs become too expensive, the government releases some of its stock onto the market; if they become too cheap, the reserve buys more porkers to keep farmers in profit. Other pro-pork policies include grants, tax incentives, cheap loans for farms and free animal immunisation—all intended to boost intensive pig farming and to keep plates loaded high with Chinese pork. According to Chatham House, a London-based think-tank, the Chinese government subsidised pork production by $22 billion in 2012. That is roughly $47 per pig.

Yet even the Communist Party can no longer control every aspect of this vast industry. That is partly because the appetite for pork is now so great—and growing so fast—that sating it depends on places far beyond China’s borders. Chinese pigs, in turn, are reshaping the environments of faraway countries.

The Communist Party prizes self-sufficiency in food. Most of the pigs China eats are indeed home-grown. But each kilogram of pork requires 6kg of feed, usually processed soy or corn. Given the scarcity of water and land in China, it cannot feed its pigs as well as its people. The upshot is that Chinese swine, which previously ate household scraps, increasingly rely on imported feed.

Ms Schneider reckons that more than half of the world’s feed crops will soon be eaten by Chinese pigs. Already in 2010 China’s soy imports accounted for more than 50% of the total global soy market. From a low base, grain imports are rising fast as well: the US Grains Council, a trade body, predicts that by 2022 China will need to import 19m-32m tonnes of corn. That equates to between a fifth and a third of the world’s entire trade in corn today.

As demand for pork rises, China’s porcine empire is sure to expand

As a result, land use is changing drastically on the other side of the world. In Brazil, more than 25m hectares of land—parts of which were once Amazon rainforest—are being used to cultivate soy (Chinese companies have not signed up to the “soy roundtable”, a voluntary association, the members of which agree not to buy soyabeans from newly deforested land). Entire species of plants and trees are being sacrificed to fatten China’s pigs. Argentina has chopped down thousands of hectares of forest and shifted its traditional cattle-breeding to remote areas to make way for soyabeans. Since 1990 the Argentine acreage given over to that crop has quadrupled: the country exports almost all of its whole soyabeans—around 8m tonnes—to China. In some areas farmers harvest two or three crops a year, using herbicides that have been linked to birth defects and increased cancer rates.

All these imports have made China ever-more exposed to global commodity prices. China has responded by buying land in other countries, some of which is used to grow feed crops or to raise pigs that are sold onto the domestic market at preferential prices. China itself is secretive about these purchases, but the International Institute for Sustainable Development, a Canadian think-tank, calculates that it has bought 5m hectares in developing countries; others think the total is higher. When Shuanghui, China’s largest pork producer, bought Smithfield Foods, an American firm, in 2013, it acquired huge stretches of Missouri and Texas. As demand for pork rises, China’s porcine empire is sure to expand.

Pigging out

Feeding the pigs is not farmers’ only concern. Their greatest fear is disease: growth slows when a pig gets sick, and, even more worryingly, swine on modern Chinese farms tend to be genetically similar (many are half-siblings), so when one gets ill, much of the herd may succumb. Farmers routinely add small doses of antibiotics to their feed, and this, too, has daunting knock-on effects. In America and Europe such practices are associated with the emergence of “superbugs”, bacteria in animals and humans that are resistant to most antibiotics. In 2009 pigs exported from China to Hong Kong were found to harbour one such bug. The mainland government acknowledged the problem, yet the use of antibiotics, hormones and growth-promoters is barely regulated.

These drugs pass into the wider food chain partly via sizzling plates of pork, and partly through the 5kg of manure that the average pig produces a day. This once-desirable substance is now a critical problem for China. Though large swathes of land have been set aside to contain it, they are poorly managed. The billions of tonnes of waste China’s livestock produce each year are one of the biggest sources of water and soil pollution in the country, according to the Ministry of Agriculture. The 16,000 dead pigs that were dumped in the tributaries of the Huangpu river, a source of Shanghai’s tap-water, after a virus outbreak in 2013, were a lurid indicator of a seeping national problem.

Porcine waste also contributes to emissions of methane and nitrous oxide, a greenhouse gas that is 300 times more potent than carbon dioxide. Intensive swine-farming is much more polluting than smallholding. So, as well as depriving Earth of the natural cooling function of the rainforests they displace, Chinese pigs contribute to global warming more directly. Greenhouse-gas emissions from Chinese agriculture increased by 35% between 1994 and 2005. The global expansion of livestock production is one of the primary causes of climate change, says Tony Weis of the University of Western Ontario, Canada, responsible for almost a fifth of emissions produced by human activity.

So although its proliferating pigs are a resonant symbol of China’s prosperity, they are also a menace. A few in China—a very few—are beginning to question the benefits of eating more and more pork. Meat consumption is beginning to plateau among the very rich; health scares have boosted sales of organic food, though it still accounts for a tiny share of agricultural production. Vegetarianism is growing, but is generally thought eccentric. The ambition of most Chinese continues to be to devour as large a slice of the pork pie as possible. In much of the rich world meat consumption is stable or falling but in the Middle Kingdom it soars unrestrained. Forget the zodiac: in today’s China, every year is the year of the pig.