Feeding and excreta collection techniques in metabolizable energy assays for ducks

Feeding and excreta collection techniques, lasting 102 h, for the determination of ME in feed ingredients for ducks are described. Eight and 32 h after feed withdrawal, all ducks received 30 g of dextrose in 100 g of water by orogastric administration. By orogastric administration, ducks received 30 g of test ingredients or dextrose (for ducks used in estimation of endogenous losses of energy and nitrogen) in 100 g of water at 48 and 54 h after feed withdrawal. The collection of excreta involved suturing a threaded plastic retainer ring to the vent and screwing a Whirl-Pak plastic bag, mounted on the top portion of a Playtex baby nurser set plastic bottle cut off 3 cm below the threads, to the retainer ring. Excreta were collected by replacing the Whirl-Pak bags at 54, 60, 72, 84, 96, and 102 h after feed withdrawal. In each of two experiments, ducks with an average weight of 3.7 kg were assigned to treatments. In Experiment 1, four ducks were assigned to each of three test ingredients (corn, dehulled oats, and wheat) and four ducks were assigned to be deprived of feed for estimation of endogenous losses of nitrogen and energy. In Experiment 2, six ducks were assigned to each of two test ingredients (corn and sorghum) and six ducks were assigned to be deprived of feed. Ducks lost an average of 537 g (Experiment 1) and 462 g (Experiment 2) during the 102-h experimental period and all the lost weight was regained within 7 d of return to full feed. Losses of nitrogen (milligrams per duck per 54 h) were 292 (Experiment 1) and 461 (Experiment 2) and energy (kilocalories per duck per 54 h) were 12.12 and 22.26 in feed-deprived group. The determined AMEn and TMEn for corn were 3.245 and 3.407, and 3.210 and 3.517 kcal/g for Experiments 1 and 2, respectively. For dehulled oats, wheat, and sorghum, the determined AMEn and TMEn were 3.464 and 3.625, 3.150 and 3.312, and 3.363 and 3.670 kcal/g, respectively.