Sampran Farm is among the operations that have succeeded with the traditional approach. It mixes herbal plants such as turmeric, fah thalai jone (andrographis paniculata), guava leaves, and cat's whisker in the meal for pigs at different ages.

The company believes in applying local wisdom by using herbal plants to strengthen animal health instead of dosing them with antibiotics that would release hazardous residues and raise concerns among consumers over hygiene.

"We've tried natural-bred farming for a few years and the result is good. Our pigs are healthy and provide better quality meat with less smell," said Subin Treeranuwat, director of Sampran Farm Co.

The herbal approach was the result of a lot of hard work and experimenting by farm staff and veterinarians in an attempt to avoid the use of antibiotics, reports Bangkokpost.com.

For example, guava leaves are put in the feed for piglets to prevent indigestion. Wild mustard and fah thalai jone are added for bigger pigs weighing between 30 and 70 kilogrammes to strengthen their lungs and livers, and turmeric fed to adult pics of 70-100 kg can promote healthiness and tender and juicy meat.

Sampran Farm also breeds pigs on a free-range farm, which is rare in local farming practice. About 6,000 pigs at its 100-rai farm in Kao Sadet in Ratchaburi are allowed to roam around, with shady areas and ponds to help them keep cool."This lessens stress at the farm and before slaughtering, which meets requirements of the international Animal Welfare rules," Mr Subin said.

Free-range farms are rare, and big raisers have opted for closed-farm systems for better disease control.

Diseases such as dysentery, babesiosis and pseudorabies have hurt the Thai swine industry, prompting the use of antibiotics but causing worry among foreign and local buyers over sanitation.

Some producers apply advanced and costly technologies to prevent pigs from contracting diseases at an early stage. Betagro Group, the country's largest pork producer, applies a specific-pathogen-free system (SPF) system to keep parent breeders free of major diseases. This involved raising them on a site in Prachinburi where no other pig farms are found for many kilometres, reducing the risk of diseases spreading. The disease-free breeding cuts the need for antibiotics.

Betagro has invested over one billion baht over the past five years for SPF pork including 270 million-baht in its abattoir, 400 million for its processing plant, and the latest investment, a 190-million-baht pedigreed pig farm. The company produces 1,500-1,700 pigs daily to supply its food business and exports.

Kriengmas Punchai, senior vice-president of swine integration, said while the market for higher-quality meat is rising, the volume remains small compared with meat from traditional farms.

Thailand produces 16 million pigs a year, over 90% from traditional farms.