On their organic diet, the cows produce about half the volume of conventional dairy cows, meaning that the supply is never enough, especially since the 2008 scandal in which tainted milk left six Chinese babies dead and sickened 300,000 people. Managers at the dairy say about two-thirds of their product goes to officials, state-owned enterprises, embassies and international schools. A limited quantity is sold at diplomatic compunds and a few select health food stores at prices nearly triple that for regular milk.
"We're not Switzerland. Our population is way too big for everybody to eat organic food," said Hou Xuejun, general manager of the Green Yard dairy.
The continued existence of the tegong, or special supply, is treated with secrecy because of public resentment over the privileges of the elite. After the Southern Weekly, a hard-hitting Guangzhou-based newspaper, published the story about the customs farm, the Central Propaganda Department banned further reporting on the subject and the article was removed from the newspaper's website.
The customs department said it did not own the farm but had signed a 10-year lease to buy vegetables.
"Because of this deal we were able to have a stable supply of vegetables for the past years and we can pay for these items at much lower costs even when the price of food is rising so much nowadays," customs spokeswoman Feng Lijing said.
The last year has seen dozens of stomach-churning scandals about tainted food. Last month, 11 people in western China died after consuming vinegar contaminated with antifreeze. Each new scandal redoubles the demand for safe food.
Although organic produce stores are cropping up in Shanghai and Beijing, prices are high. Desperate for clean food at affordable prices, some Chinese families have formed cooperatives to buy directly from farmers — their own version of special supply.
"There is not enough supply of organic food, there aren't so many farmers who really know how to produce organically, and if you found a farm, it is too expensive for ordinary people," said Liu Yujing, a Beijing homemaker who founded a 100-family cooperative last year.
The mother of a 4-year-old girl, Liu was motivated by the revelations of melamine-tainted milk. "I know you can buy some organic food in shops, but I don't trust that either. We've heard a lot of them are fake."
China's sports teams have enacted strict bans on athletes eating pork because of the fear that clenbuterol, a common but illegal steroid fed to pigs, can cause false positives on drug tests. Female judo champion Tong Wen was banned from competing internationally last year after a test showed traces of the drug, but the ban by the International Judo Federation was overturned in February after she said she had never knowingly ingested clenbuterol.
"Now we have a special team that takes care of procuring food. We are more cautious than ever before. We buy pork only from organic farms through a channel that the government has approved," said judo coach Wu Weifeng.
Much of the pork for the elite is procured through the 2nd Commercial Bureau, which has a subsidiary that slaughters 50,000 pigs a year at a farm in Sanhe, Hebei province, according to Caixin, a business magazine.
The magazine said most of the pork went to the special supply and quoted a manager as saying, "Sometimes raising pigs is about politics too."
Nicole Liu of The Times' Beijing bureau contributed to this report.