Two fattening experiments are reported with 60 cross-bred bulls. In the first experiment three pen groups (9–16 months old) of eight Simmental, eight Friesian and eight Jersey crosses, from Boran and Barca dams, were fed for 98 days on a common diet consisting of maize cobs, molasses and concentrate. There were no significant differences among sire or dam breeds, with the Barca cross bulls performing non-significantly better than the Boran crosses. Simmentals and Friesians consumed about the same amount of feed and the latter were the most efficient feed converters. In the second experiment, 36 bulls ranging from 11 to 18 months of age were fed for 51 days diets consisting of either 30 or 50% maize stalks and concentrate; maize stalks were replaced by maize/sorghum silage for the next 61 days. There were no significant differences in rate of gain between sire breeds. Bulls from Boran dams gained faster (P < 0·01) than those from Horro dams while a higher (P < 0·05) daily gain was recorded for the diet with the lower than with the higher percentage of maize stalks.