The present invention relates to the use of F4+ non-pathogenic Escherichia coli strains to promote growth in an animal. The present invention also relates to the use of such strains to homogenize growth among a herd of animals. More specifically, the animal(s) of interest in the present invention are those wherein growth promotion or growth homogenization are desired goals, such as animals reared for meat production. The present invention further relates to a method for promoting growth of an animal as well as a method for homogenizing growth among a herd of animals.