On August 23, Dong Nai's livestock and fisheries authorities, together with relevant agencies, culled nearly 900 more affected pigs, bringing the total destroyed at five farms to nearly 3,000.
Around 1,000 pigs remain at a sixth farm, where the owner has yet to voluntarily cull the animals. Concerned agencies are working with the farm to deal with the remaining pigs.
The case emerged after inspections between July 28 and August 5 found nearly 4,000 pigs at six farms in four communes and wards testing positive for Salbutamol, a beta-agonist banned for use in livestock farming.
According to Dong Nai's agriculture and environment authorities, the farms had not registered their livestock operations and specialised in fattening pigs. They bought animals weighing around 90-100 kg and allegedly mixed the banned substance into feed to accelerate weight gain.
The practice posed food safety risks and could harm consumers. Documents relating to all six farms are being completed for referral to police for further investigation in accordance with regulations.
Dong Nai is home to thousands of pig farms, but only a small number specialise in this type of short-term fattening, mostly operated by livestock traders. Authorities said no use of Salbutamol had so far been detected at conventional pig farms in the city.