The Effect of the Duration of the Excreta Collection Period on the True Metabolizable Energy Values of Feedingstuffs with Slow Rates of Passage

An experiment was made to study the effect of the duration of the excreta collection period on the true metabolizable energy (TME) values of 8 samples of dehydrated alfalfa, 2 samples of menhaden fish meal, and one each of peanut skins and wheat. The TME values of alfalfa and fish meal were lower and less variable when the collection period was extended from 24 to 48 hr. This confirms that the residues of these feedingstuffs are not completely voided within 24 hr. The TME value of wheat was not changed by extending the collection period. The TME values of peanut skins were erratic and the product requires further investigation. The TME values of alfalfa tended to increase as the protein content increased and as the sum of crude fibre + ash decreased. It is recommended that the excreta collection period be extended beyond 24 hr for materials having slow rates of passage.