Effect of Carrier on the True Metabolizable Energy of Corn Oil

The true metabolizable energy (TME) of corn oil was determined using both practical and purified carriers. When assayed with “high-fat” practical carriers (corn or mixed feed), the TME of corn oil averaged 9.21 kcal/g compared with a significantly (P≤.05) higher value of 9.66 kcal/g when assayed with “low-fat” carriers (soybean meal or ether-extracted feed). As the latter value exceeded the gross energy of fats, it was concluded that the addition of corn oil to the low fat carriers enhanced the absorption of these substances, and this was reflected in the TME of the corn oil by extrapolation. It was found that neither glucose nor corn starch alone was satisfactory as a carrier for determining the TME of corn oil. Combinations of glucose and corn starch had TME values equal to their gross energies, indicating virtually complete absorption. The TME of corn oil determined using these carriers was 8.90 kcal/g, which was not significantly different (P≤.05) than when high fat practical carriers were used. Glucose-corn starch carriers may find application in evaluating the interactions between supplemental fats and basal diets in energy determinations.