The densities of infective nematode larvae (L3/m2) in the night holding places (locally called "correos") of 2 traditionally kept N'Dama herds were estimated at weekly intervals throughout an entire rainy season. Herd 1 moved correos every 3 weeks whereas herd 2 remained in the same area for most of the rainy season. Removal to a new correo was invariably accompanied by a drastic drop of L3/m2. Conversely, L3/m2 increased rapidly up to values of more than 1,000 when the herds used the same night holding place for more than 3 weeks. Calves kept in herds with frequent changes of the correo showed significantly lower nematode egg counts and higher growth rates during the rainy season, combined with a reduced weight loss during the following dry season. The results of this study indicate that a regular frequent change of the correo is an effective method of reducing nematode infection risk and increasing calf growth and that this might be a sustainable part of an integrated strategic programme to control gastrointestinal nematode infections wherever correos are used.