Antibiotic growth promoters (AGPs) are used to describe any medicine that destroys or inhibits bacteria and is administered at a low, sub therapeutic dose.

They have been widely used to improve performance of food animals.

Antimicrobials are given to broiler chicken in order to control diseases such as necrotic enteritis caused by Clostridium perfringens, and also to promote faster growth and improve conversion rates.

The effects of those drugs are not fully understood, but the potential of the intestinal microbiota in increasing feed efficiency has been shown.