The study was designed to evaluate a physical model performance of a cow-calf operation system for the semi-arid region, in Brazil. Native pastures (caatinga) were grazed during the rainy season and buffel grass pastures over the rest of the year. Leucaena supplementation, under rotational grazing and as hay, was provided during the dry season. Performance parameters, monitored from November 1991 to October 1995, showed a 72.8% annual calving rate and a very low mortality rate. Weaning weights of calves averaged 153.4 kg at 205 days. Production of calf weaned was 109.5 kg/cow run/year and 25.5 kg/ha/year. Performance data can be concluded to be very promising if considered that above half the total area was covered by native pastures and that leucaena hay supplementation was strongly limited by occurrence of a severe drought period.
