Metabolizable energy values determined with intact and cecectomized roosters

Mature White Leghorn roosters that were intact or cecectomized were used to determine the ME of a diet. Seven intact and 7 cecectomized roosters were fasted for 3 d, with total excreta collection on d 2 and 3. Approximately 1 wk after completion of the trial, the same roosters were force-fed 28 g of a diet that was 85% corn and 15% soybean meal after a 1-d fast. Excreta were collected from d 2 and 3 and dried. There was no difference in the energy and nitrogen excreted by intact and cecectomized roosters when they were fasted for 3 d. The energy and nitrogen excreted by cecectomized roosters were greater than by intact roosters when they were fed the test diet. As a result, the AME, TME, AME(n), and TME(n) were all larger from intact roosters than from cecectomized roosters. Our results suggest that intact roosters should be used to determine the energy content of ingredients that will be fed to commercial flocks.