Two hundred eighty days old male broiler chicks (Ross strain) were randomly distributed into seven groups with four replicates (10 birds in each replicate) and were fed diets supplemented with different dietary fat sources. The results indicated that the different dietary treatments did not affect weight gain, feed intake and feed conversion ratio at 21 d (P>0.05). However, addition of dietary fats to diets increased body weight gain and improved feed conversion ratio in grower (22-42 d) and whole period (7-42 d) of the experiment (P<0.01). Chicks fed diets supplemented with 6% of tallow or soybean oil and 3% tallow+3% soybean oil had the most body weight gain and the best value for feed conversion ratio (P<0.01). There were no signifi-cant differences between carcass characteristics (except for abdominal fat pad) due to dietary treatments (P>0.05). Increasing the dietary fat level increased significantly abdominal fat pad deposition (P<0.01). Abdominal fat pad deposition was significantly higher in birds fed diets supplemented with dietary fats than in those fed control diet (P<0.01).
