Effect of Conservation Method on Digestibility, Nitrogen Balance, and Intake of Alfalfa

Alfalfa diets were fed to growing wethers to examine factors lowering intakes of alfalfa silage and to identify dietary characteristics related to voluntary intake. Direct-cut silage (Silage), direct-cut silage dried to the same dry matter as hay (Drysil), heat-dried hay (Hay), hay with water added to give the same dry matter as silage (Wethay), direct-cut silage treated with .5% of 2:1 formaldehyde (37%):formic acid (90%) mix at ensiling (Formal), and 24-h wilted silage (Wilted) were made from forage cut and chopped similarly. Digestible dry matter of Silage (50.5%) was lower than Formal (54.5%)and Wethay (57.4%)with other diets intermediate. Number of meals per day tended to be greatest for the Silage diets. Eating rates were highest for Formal and Wilted diets. More than 1.81% of nitrogen was in the acid detergent fiber insoluble fraction, resulting in low nitrogen digestibilities and negative nitrogen balances for Silage, Drysil, and Formal diets. Voluntary digestible energy intakes (Silage, 190; Drysil, 177; Hay, 202; Wethay, 228; Formal, 225; Wilted, 200 kcal/weight kg.7 s) were not related to moisture content of the forages. Digestibility, density, rate of digestion of cell wall constituents, and behavioral patterns were discussed as possible factors related to intake.