Influence of caloric density on energy intake by dairy cows

Twenty-four Holstein cows were fed mixed diets of alfalfa hay and concentrate in a series of periods to determine the relationship between caloric density (mcal digestible energy/liter) of the diet and energy intake. Five diets with caloric densities of .58, .63, .68, .84, and 1.17 (as-fed form) were used. Steers were fed the diets in digestion trials to determine maintenance digestibility. Intake of digestible energy was adjusted for intake. Means of digestible energy intakes (kcal/day per kg. 75) were: 291.7, 324.0, 370.0, 371.4, and 369.1 for diets with caloric densities of .58, .63, .68, .68, .84, and 1.17. Physical fill was limiting for the two most dilute diets. The diet with caloric density of .68 represented the point above which physiological regulation was employed by the animals. The relationship between digestible energy intake (kcal/day per kg-75) body weight (Y) and caloric density (mcal/liter dry matter, as fed form) (X) was Y = 759.2X-148.4, simple correlation .99, for diets with caloric densities of .58, .63, and .68. Potential uses of this relationship in maximizing forage utilization and formulating diets to meet specific energy requirements are cited.