Determination of metabolizable energy contents of feed ingredients for ducks

The objective of the present experiments was to determine the AMEn and TMEn of various feed ingredients used in duck diets. In each of two experiments, 48 mature, male, White Pekin ducks were assigned in pairs to 24 cages based on initial weight. In each experiment, 12 ducks were assigned to each of three test ingredients and 12 ducks received dextrose for determination of endogenous losses of nitrogen and energy. The test ingredients were tube-fed in wet form and consisted of corn, barley, and pearl millet in Experiment 1, and corn, sorghum, and triticale in Experiment 2. Feed was withdrawn 48 h prior to feeding the test ingredients and ducks were tube-fed 30 g of dextrose in 100 mL of water at 8 and 32 h after feed withdrawal. Ducks were tube-fed 30 g of their assigned test ingredient in 100 mL of water at 48 and 54 h after feed withdrawal. Ducks used in estimating endogenous nitrogen and energy losses were tube-fed 30 g of dextrose in 100 mL of water at 48 and 54 h after feed withdrawal. The method of excreta collection utilized was surgical fixation of a collection apparatus to the vent area of ducks to facilitate total collection of excreta. Collection of excreta was initiated at the first feeding of test ingredients and was continued for a total of 54 h. In Experiment 1, the AMEn and TMEn of corn, barley, and pearl millet on an as-fed basis were determined to be 3.208 and 3.339, 2.730 and 2.863, and 3.350 and 3.484 kcal/g, respectively. In Experiment 2, the AMEn and TMEn of corn, sorghum, and triticale on an as-fed basis were determined to be 3.151 and 3.459, 3.260 and 3.567, and 2.757 and 3.065 kcal/g, respectively. In conclusion, the use of the modified TME assay, in addition to total collection of excreta from individual ducks, provides a means of accurately estimating the ME content of feed ingredients used to formulate diets for ducks.