The present invention relates to a novel feed composition for animals, for example poultry, comprising as active ingredient benzoic acid, derivatives or metabolites thereof, in combination with a mixture of at least two active compounds selected from the group consisting of thymol, eugenol and piperine. The inventors found that in addition to the well known function of benzoic acid, this compound can be used as a potential growth promoter when it is combined with a mixture of at least two active compounds selected from the group consisting of thymol, eugenol and piperine. In particular the inventors have been able to demonstrate that a mixture of these chemical compounds present in different parts of plants, used in synergy and in combination with an appropriate amount of benzoic acid, exhibits, in totally unexpected manner, the effects sought by the present invention of improving the digestibility of poultry feed, i.e. for improving feed conversion ratio and/or daily weight gain in animal.