Endogenous Energy Losses of Fed Versus Fasted Roosters

Abstract

A series of experiments was conducted to determine the influence of energy intake on the endogenous energy excretion of Single Comb White Leghorn (SCWL) roosters. In the first study, 0, 12.5, and 25.0 g of a 50% glucose-corn starch mixture were each fed to 32 roosters previously fasted for 24 hr. Energy and nitrogen excretion for the 24 hr postfeeding decreased significantly as energy intake was increased.In the second study, eight SCWL roosters were assigned to each of six feeding regimens: fasted, 20 g glucose, 20 g yellow corn, 20 g yellow corn plus 20 g glucose, 20 g soybean meal, and 20 g soybean meal plus 20 g glucose. Energy and nitrogen excretion for the 24-hr postfeeding period were determined. Roosters receiving glucose voided less energy and nitrogen than did those in corresponding treatments without glucose. This reduction was significant (P<.05) in roosters fed soybean meal plus glucose.These results suggest that endogenous energy loss is inversely related to level of energy intake, presumably due to a sparing effect on the catabolism of body tissue. Possible implications of this effect on true metabolizable energy assays are discussed.