The invention relates to the use of at least 10 ppm and up to 500 ppm, based on the total composition of a berberine, obtained naturally or synthetically, with the formula (I), wherein the berberine is in the form of a salt selected from berberine hydrochloride or berberine sulfate present at a concentration of at least 95% by weight with respect to the total weight of the berberine composition, in an animal nutritional composition, as a feed additive for fattening.
