The effect of diet protein and energy levels on the growth performance and feather production of slaughter ostriches under feedlot conditions.   Lucerne , maize and ostrich carcass meal were used to formulate nine diets supplying three protein levels (14, 16 and 18%), each with three roughage : concentrate ratios which were fed to six birds per group. Group feed intake and individual livemasses were recorded weekly from 250 to 462 days of age under feedlot conditions. Growth rate and feed conversion ratio were calculated for each group over the livemass interval 60-110 kg. The average growth rate varied from 129 to 240 9 between groups with an overall average of 189 9 per day, whereas the feed conversion ratio varied from 10,0 to 15,4 with an average of 12,8. Pluckings of the body feathers had an overall mean mass of 707 g. Differences between feather yields were not significant (P> 0,05). In terms of growth rate and feed consumption a diet with a protein level of 14% containing 35% dry lucerne gave the best results with a feed conversion ratio of 10,0.