Botanicals have been proposed as a substitute for antimicrobials in swine diets because of potential natural antibacterial activity. Garlic (Allium sativam), a botanical that grows in Iowa, was compared with a standard antibacterial nursery dietary regimen. A trial conducted in 1997 had inclusion levels of 0.0, 0.5, 2.5 and 5%. These levels of garlic generally depressed feed intake and average daily gain in nursery pigs and depressed performance compared with the control diet with Mecadox. Muscle samples from the garlic-fed pigs all had “very objectionable” or “extremely objectionable” off-flavors.

This trial fed inclusion levels of 0.00, 0.10, 0.25, and 0.50% garlic, levels that hopefully would be low enough not to depress performance or alter meat flavors. Pigs fed diets without Mecadox demonstrated significantly poorer performance than with Mecadox inclusion. Based upon this and the 1997 studies at Iowa State University, pigs fed diets without Mecadox performed less well than those fed Mecadox. The addition of garlic did not enhance pig performance.