A group of experiments was designed with a developed and validated simulation model for dairy East Friesian ewes, to quantify the effect of the supplement inclusion to different stocking rates, on the productive and reproductive parameters of grazing dairy ewes. The experiments was carried out simulating animals of 75±0.s kg of weight and 3,0 years old average, varying stocking rate in ranges of 1, 3, 5, 7 and 9 animals per hectare, beginning the simulation in January, duration of the flushing 45 days, with a period of nursing 200 days, potential production of 450 milk liter per lactation, lambs to be weaned at 70 days. The animals are grazing Festuca arundinacea pasture, with instantaneous initial availability of 1500 kg of d1y matter per hectare. The productive systems with supplement showed significantly bigger productive and reproductive parameters on the average (p <0,05) that those without supplement. That parameters were: ovulation rates; birth, weaning and parturition weight; daily production milk; lactation dairy production and dry matter intake.