The Effects of Level of Dietary Inclusion and of Calcium on the True Metabolizable Energy Values of Fats

Three experiments were made to investigate the effects of level of dietary inclusion and of calcium on the true metabolizable energy (T.M.E.) values of fats. In the first experiment graded levels of inedible beef tallow were added to two basal diets which differed in limestone content. The second experiment was similar but the fat was soybean oil. In the third experiment four levels of limestone and four levels of inedible tallow, 16 diets, were studied. The level of dietary inclusion affected the T.M.E. values attributed to tallow, and to soybean oil when fed in conjunction with a high calcium basal diet. The effects were complex and probably reflected the interactions between the fats and the other dietary components. In general an increase in the level of dietary calcium decreased the T.M.E. value of tallow but had a much smaller effect on the T.M.E. value of soybean oil. Again, the effects were complex and varied with the level of inclusion of the fats.