LAUSR

Abstract This study investigated the effects of formic acid (FA) treatment for ensiling cassava foliage (CF) and sweet potato vine (SPV) with corn or barley grains on ruminal and total tract nutrient digestion, nitrogen (N) utilization, and urea metabolism in sheep. Four wethers fitted with ruminal and duodenal cannulae were assigned to a 4 × 4 Latin square design with a 2 × 2 factorial arrangement with ensiling treatment and grain source as the main effects. Sheep were fed four mixed diets containing the untreated CF and SPV silages with rolled barley or steam- flaked corn, or the FA-treated silages with rolled barley or steam-flaked corn. All experimental diets were formulated to contain 600 g forage (CF silage:SPV silage:oat hay, 150:150:300) and 400 g concentrate per kg dry matter (DM). The diets (120 g crude protein/kg DM; 10.6 and 11.2 MJ metabolizable energy/kg DM for the barley- and corn-based diets, respectively) were provided at 22 g/kg of body weight on a DM basis. The dietary treatments did not affect DM intake, but the total tract DM digestibility was higher for the corn-based diets than for the barley-based diets. The ruminal digestion of non-fiber carbohydrate (NFC) was higher (P