A second round of tests on pigs from the farm in Changhua County, owned by Wu Tzai-wang in Changhua County, have proved positive. It followed confirmation by health officials last month that some pork produced at Wu's farm was found to contain ractopamine.

Kuo Chou-che, director of the Changhua county government's Animal Disease Control Centre said Wu was prohibited from selling any more than 200 pigs from his farm until the next tests results came back negative.

He said some local farmers have taken to using ractopamine after being convinced by animal feed additive traders that the ractopamine can boost growth of lean meat in pigs.

Meanwhile, officials in Nantou county's govenment health department has been quick to assure the consumers that the pork produced in the county is free of ractopamine.

Officials from the Health Bureau issued said that tests for ractopamine residue in several pork samples from farms across in the county have benn negative and the public has no need to be concerned. They say that regular checks on local pigs will continue in a bid to strengthen food safety for consumers, and encourage the public to buy products from reoutable companies.

Ractopamine is used to enhance lean growth and performacne in fisnihing pigs. It is legal to use as a feed additive in more than 20 countries, but it is banned in Taiwan.

The local use of ractopamine was highlighted in July after two shipments of pork from the United States were found to contain residues of the veterinary drug. The substance is permitted for use in the US.

The issue caused a panic among consumers, with Department of Health (DOH) officials having to assure the public that the government ban on the use of ractopamine in pigs remains in place, and imports of pork containing residue of the drug are still prohibited.