A composition comprising: (a) 10 - 90 wt%. of an organic acid selected from the group consisting of acetic, propionic, butyric and mixtures thereof, (b) 1 - 90 wt.% of ethoxylated castor oil surfactant having an HLB from 4 to 18 and a molar ratio of 1 molecule of castor oil to 1 - 200 molecules of ethylene oxide, (c) 0 - 20 wt.% of antimicrobial terpenes, or essential oils such as allyl disulfide, thymol, citral, eugenol, carvacrol, limonene or carvone. The composition is used for treating animal feed, preferably extruded animal feed.
