The present invention relates to the method of producing an antimicrobial composition comprising step of splitting a refined (preferably degummed, bleached and deodorised) lauric oil (preferably coconut oil, palm kernel oil or their mixtures). The invention further relates to antimicrobial compositions comprising 90% of free fatty acids (preferably: 0-5% caproic acid, 1-15% caprylic acid, 1-15% capric acid and 35-70% lauric acid), to the animal feed comprising said composition and to their uses.