7 January 2000

Pig bacteria quandary

PIG carcasses may carry only low levels of salmonella contamination, but there is evidence of infection in slaughtered pigs from about 45% of farms, according to a recent abattoir study.

The MAFF-funded study by the Vet Lab Agencys Rob Davies also reveals that a third of these infected farms had either Salmonella typhimurium DT104 or DT104B, a strain with multiple antibiotic resistance. Salmonella typhimurium DT104 or DT104B was found on about 3% of carcasses, according to the report in Vet Record.

It explains that low-level salmonella contamination when combined with poor food handling practice in kitchens can allow the bacteria to multiply, posing a risk to human health. The actual contribution of pigmeat to human salmonellosis is unknown.

It is only possible to contain – rather than reduce – bacteria in the slaughter process, so control measures should be established on farms, it advises.

Danish farms have managed to reduce contamination to 1% of pork carcasses, and studies show that higher risks are posed by large herds and sourcing pigs from dealers.

It may also be difficult to control salmonella in outdoor breeding herds, which are becoming more popular in the UK, according to the report.

But liquid feeding and home-mixing may help control bacteria, providing wild birds are not allowed to contaminate feed.

It may also be beneficial to break the cycle of infection by segregated weaning, split-site production, keeping pigs in smaller groups, avoiding mixing and having an all-in/all-out policy, says the report. &#42