This study was conducted to determine the effect of two different levels of supplementary feed and two different stocking rates on the production of grazing ostriches. One hundred and seventy ostriches were randomly allocated to four groups and kept on irrigated lucerne pasture with or without supplementary feed from approximately 58 kg to a target weight of 95 kg. The ostriches rotationally grazed lucerne pasture at one of two stocking rates, i.e. 15 birds/ha or 10 birds/ha and were fed one of two levels of supplement i.e. 0 g or 800 g feed/d formulated according to the nutrient requirements of the relevant group of birds. Data were analyzed by ANOVA. There was no interaction between the supplementary feed and stocking rate regarding mean live weight at 54 weeks of age and feed conversion ration (FCR). Data were provided as the two main effects of level of supplementation and stocking rate. Significant differences in mean live weight at 54 weeks of age and FCR of the birds were observed between the different levels of supplementary feed. The parameters measured for the two different stocking rates used in this study (10 birds/ha vs. 15 birds/ha) did not differ from each other and did not influence either mean live weight at 54 weeks of age, average daily gain (ADG) or FCR. The two groups which received 800 g supplementary feed/d reached slaughter weight (95 kg) within the set of 54 weeks of grazing for the trial, while the two groups which received no supplementary feed did not achieve slaughter weight by 54 weeks on the pasture. Ostriches receiving supplementation of 800 g/bird/day had significantly better FCR’s than birds receiving no supplementation. There was a significant interaction between level of supplementary feed and stocking rate regarding ADG of the birds. As stocking rate increased, average daily gains of birds receiving no supplementary feed declined. This study indicates that ostriches being kept on grazing and receiving supplementary feed will exhibit improved and faster growth rates than ostriches which only have access to grazing and receive no supplementary feed.