Four complete isonitrogenous (crude protein 13%) rations with 0 (T1), 5 (T2), 10 (T3) and 15 (T4) per cent calcium soap from red palm oil (protected fat) were formulated and evaluated using four Deccani lambs (19.32 +/- 0.82 kg) in a completely randomized design at the end of a growth trial. The average daily dry matter intake (% body weight or g/kg W0.75 per day) in lambs fed ration T4 was significantly (p < 0.05) lower than in those fed rations T1, T2, and T3. There was no significant difference in the digestibility of proximate principles and cell-wall constituents except for ether extract (EE) and cellulose. EE digestibility was significantly (p < 0.05) higher by 15.71, 14.65 and 11.56 percentage units, respectively in lambs fed rations T2, T3 and T4 as compared to those fed ration T1. Ration T4 had significantly (p < 0.05) lower cellulose digestibility than rations T1, T2 and T3. Nitrogen and phosphorous balances (g/day) were not significantly (p > 0.05) different among the four rations. Calcium balance (g/day) was higher by 0.65, 1.39 and 1.40, respectively, in lambs fed rations T2 (p > 0.05) and T3 and T4 (p < 0.05) in comparison to those fed ration T1. Digestible crude protein and total digestible nutrients content (g/kg DM) of rations were not significantly (p > 0.05) different among the four rations. It is concluded that calcium soap from red palm oil can be supplemented up to 10% level as a concentrated energy source in the rations of Deccani lambs without any adverse effect on dry matter intake and cellulose digestibility.