A deterministic, dynamic simulation model for grazing and fatlening steers is presented. In orderto simulate grazing, a fixed number of paddocks rotationally grazed is asigned. Dry maller intake, selection and supplementation are among the factors included to predict animal performance. Validation of the model showed a trend to overestimate conserved forage from the system and the performance of the steers in the feedlol. Simulated animal performance during the grazing period showed a reasonable coincidence with field experiments. Using the model, a potential beef production inthe range of 700 to 900 kg/ha is estimated with stocking rates of 2.0 to 2.6 Sleers/ha respectively, in the dryland of the IX Región, Temuco. A delay inthe date of conservation increased the total amount of conserved forage, however, althoughthis meanta longer period ofthesteers inthefeedlol. Changing selling and buying prices of the steers affected total income of the system.