Effect of Diet Forage-to-Concentrate Ratio on Partition of Dietary Energy and Nutrients in Fed and Fasted Sheep

Abstract

Sano, H., Ito, T. and Terashima, Y. 2004. Effect of diet forage-to-concentrate ratio on partition of dietary energy and nutrients in fed and fasted sheep. J. Appl. Anim. Res., 25: 101–108. A total collection method and open-circuit calorimetry were used to measure partition of dietary energy and protein and nutrient oxidation in sheep fed on a high roughage diet (HR diet) or a high concentrate diet (HC diet). Fasting metabolism was also determined. Digestible and metabolizable energy intakes did not differ between the diets. Oxygen consumption and carbon dioxide and methane emissions were similar in both diets and decreased (P=0.0001) during fasting. Digestible nitrogen (N) intake was greater (P=0.03) for the HC diet, whereas N balance remained unchanged due to enhanced (P=0.005) urinary N excretion. Heat production was similar in both diets and decreased (P=0.0002) during fasting. Carbohydrate and fat oxidation did not differ between the diets, whereas protein oxidation was greater (P=0.02) for the HC diet than for the HR diet. During fasting protein oxidation remained unchanged., carbohydrate oxidation decreased (P=0.0003) and fat oxidation tended to increase (P=0.08). In this study, type of diet influenced energy and protein partition in sheep. However, these results were not entirely attributed to type of diet because energy and protein intakes influenced these variables.