Pig feed: Potential effects of antimicrobial carryover

Medicated feed premixes are often included in compound feeds. Hence, some antibiotic carryover can occur when a feed miller switches from producing one feed type to the other. What levels would be acceptable and is it known what effects this may have? Following the recent Dutch comments by their Ministry of Economics, Agriculture and Innovation to reduce the use of antibiotics in agriculture by 50% by 2013, one of the measures included the possibility of banning the use of medicated feed premix