Digestible Energy Intake of Complete Diets by Wethers and Lactating Ewes

Abstract

The two feeding trials were designed to study the relationship between voluntary digestible energy intake (DEI) and selected dietary characteristics. Animals used were 24 growing wethers (34.7 kg, Trial 1), and 21 crossbred ewes (62.8 kg, Trial 2) suckling single lambs. The six alfalfa-concentrate diets (A through F) fed in both trials had a wide range of density (g/ml), and estimated digestible energy (DE) content between 2.2 and 3.5 kcal/g. Digestible dry matter (DDM), and energy, measured during the 8 day ad libitum intake phase (Trial 1), were greatest for diet F. In vitro rates of digestion of cell wall constituents (CWC) contributed to the significance of DEI predictions. Ad libitum DEI/weight^.75/day by growing sheep of 217, 262, 239 and 253 kcal and by lactating ewes of 318, 311, 336 and 453 kcal for diets A through D were probably limited by volume, undigested CWC or other fill determining components. Average DEI/weight^.75/day of the diets had a plateau of 255 kcal for growing sheep and 416 kcal for lactating ewes which represented their respective energy demands. These trials indicated both physical and physiological components of intake regulation, and regression analyses showed that digestibility, density, CWC, and rate of digestion made significant contributions to intake prediction. Copyright © 1976. American Society of Animal Science . Copyright 1976 by American Society of Animal Science.