The complete ban on the use of antibiotics as growth promoters on Danish farms has not led to increases in food-poisoning bacteria as some feared. The Danish experience is seen as a test case for an impending European Union ban.
According to a report in the New Scientist, low doses of antibiotics have been given to livestock since the 1950s to make them more productive. As a result, many bacteria have become resistant to antibiotics, and concern that this resistance might be passed on to bacteria dangerous to people prompted the EU to ban the use of most antibiotics as growth promoters in 1999. The remaining four will be phased out in 2006, but Denmark opted for a complete ban in 1998.
Mary Evans and Henrik Wegener at the Danish Veterinary Institute in Copenhagen looked for trends in the prevalence of Salmonella and Campylobacter in around 450,000 meat samples from chickens and 830,000 pig samples taken from 1995 to 2001. Both can cause food poisoning in humans, but are rarely a problem for animals.
To their surprise the ban had no detectable effect on the prevalence of these bacteria. Wegener said he had expected to see an increase in bacteria in meat samples because chickens reared without growth promoters tend to produce larger amounts of more watery faeces that are more likely to contaminate the carcass during slaughter. Also, four of the antibiotics phased out kill Campylobacter.
However, there has been a 50 per cent rise in the use of antibiotics to control disease since the Danish ban. "The bacteria don't care if you call them growth promoters or therapeutic drugs," said Wegener. Part of this increase is tied to secondary infections prompted by a viral epidemic in pigs. However, it seems some are also needed to control infections that would otherwise have been suppressed by growth promoters. Overall, though, antibiotic use is less than half what it was during the 1994 peak.
Some believe a fundamental shift away from intensive farming, in which animals are kept in close proximity in often stressful conditions, is the only way to further reduce the amount of antibiotics used in farming. "The only solution is a complete change in the way we keep animals," said Richard Young of Britain's Soil Association.