This study was conducted to evaluate the effects of replacing soybean oil (SBO), typical in broiler diets, with a less expensive commercial fat blend, Kofat (KOF). A 2 x 2 x 2 factorial experimental design was used to study the interactions of the two fat sources, SBO and KOF, at two levels of metabolizable energy (ME) (low and normal) with the inclusion or not of an enzyme, Tomoko (TOM), in broiler diets. The broilers were fed ad libitum in cages from 1 to 30 days of age. Two hundred one-day-old male (Ross 308) chicks were distributed among 40 cages with five replicates per treatment, and received a starter diet from 1 to 16 days and a finisher diet for days 17 to 30. Cumulative feed intake was not influenced by fat source, energy level or TOM supplementation for the starter, finisher or total periods. For the total period (1 to 30 days), energy x enzyme interaction was significant for bodyweight gain (BWG) and feed conversion ratio (FCR). The TOM supplementation had a positive effect on the low energy diet and a negative effect on the normal energy diet with respect to BWG and FCR. The TOM enzyme was able to restore the nutritional value in the low energy diet. Fat source had no influence on performance of broilers during the experiment period. It was concluded that KOF as a source of fat and the enzyme, TOM at a rate of 0.05%, can be included in a broiler diet where the ME level has been reduced by 414 kJ/kg during the starter and finisher periods.