An experiment was conducted to determine the effect of dietary Ca levels on True Metabolizable Energy (TME) and TME with nitrogen correction (TME ) values of 3 fat sources (cotton seed oil, animal fat and n a 50:50 mixture). The fats were each added at the level of 0, 3, 6 and 9% to 2 basal low and high Ca content diets. The true metabolizable energy of experimental diets was determined using precision fed rooster assay method. The TME and TME of 3 fat sources were obtained through regression and extrapolation to 100% fat n replacement in basal diets. The addition of Ca carbonate to the zero added fat diet significantly (p<0.05) reduced the TME of diet (3348 vs. 3294 kcal kgG ). The true metabolizable energy of animal fat was significantly (p<0.05) lower than that of cotton seed oil (8619 vs. 9974 kcal kgG1). However, the TME of fat and oil mixture was similar to that of oil value (9974 vs. 9915 kcal kgG1). The TME of fat decreased as the level of fat increased (p<0.01) when it was calculated by the difference method. Addition of Ca carbonate to the diets contained any sources of fat significantly (p<0.05) reduced the TME value of fat. The metabolizable energy of fat linearly (p<0.05) reduced in response to increase in dietary fat levels as determined by difference method.

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