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Castor cake shows potential for use in sheep feed in semi-arid regions, but as a limitation, contains ricin, which can cause poisoning. The aim of his study was to evaluate the influence of diets containing castor cake on feeding behaviour, intake and performance in sheep. Twenty Morada Nova sheep were distributed into two randomised blocks with five treatments (untreated castor cake, castor cake treated with limestone, with urea, with monodicalcium phosphate and autoclaved) and four replications. Nutrient intake was not influenced by the detoxification treatments, with the animals displaying no symptoms of poisoning. There was no difference in feeding behaviour between treatments for most of the variables, and the possible rejection of the untreated cake by the sheep was not confirmed. It was found that animals fed diets containing autoclaved castor cake performed better than those which received untreated cake. Although the animals fed castor cake treated with monodicalcium phosphate were not superior to those fed untreated cake, they had a 27.3% greater average daily gain, consumed 10.5% less feed to gain 1 kg, and took 24 days less to gain 12 kg. The finishing of sheep fed diets containing autoclaved castor cake shows a superior response to the finishing of these animals fed diets containing untreated castor cake or detoxified with urea. Furthermore, animals finished on diets containing cake detoxified with monodicalcium phosphate or limestone show an intermediate response.