Banning antimicrobial growth promoters in feedstuffs does not result in increased therapeutic use of antibiotics in medicated feed in pig farming

Objective We analysed prescription patterns for medicated feedstuffs to find out whether the ban on nutritive antimicrobial growth promotion introduced in Switzerland in 1999 had caused an increase in the therapeutic use of antimicrobial agents given orally to piglets and fattening pigs. Methods From 1996 to 2001, a total of 6427 prescriptions were evaluated for medicated pig feed delivered to pig farms in the Swiss canton of St Gall. Prescribed daily doses (PDD) were derived for 14 active ingredients. The overall amount and the potency of antimicrobial agents were measured in relation to the size of the pig population (PDD/population). Results The use of antimicrobial agents decreased between 1996 (1200 kg) and 1999 (708 kg) and increased thereafter from 779kg in 2000 to 936kg in 2001. The PDD/population (6.1 in 1996 and 3.6 in 1999) remained low (3.3 in 2000 and 3.4 in 2001). The difference between the two parameters can be explained by changes in prescribing patterns, namely a reduction in antimicrobial therapy of respiratory diseases in fattening pigs and a shift to antimicrobial treatment of gastrointestinal-tract infections in piglets using drugs with a high PDD. Copyright (C) 2003 John Wiley Sons, Ltd.