Intake, digestibility and energy utilization of corrugated paper diets

Diets containing 25 or 60% corrugated paper were fed at maintenance levels or ad libitum to dairy heifers to measure intake, digestibility and energy utilization. Intakes were similar for the two diets but dry matter, energy, fiber and protein digestibilities were lower for the 60% diet, resulting in negative energy balance. Digestibilities of dry matter, energy and fiber were lower when fed ad libitum than at maintenance levels; the depressions (10-20% units per unit of maintenance) were larger than in forage or forage-grain diets (5-10% units per maintenance unit). By regression, corrugated paper was estimated to have 45% dry matter digestibility, 24% neutral detergent fiber digestibility and 0.29 Mcal kg^-1 net energy for maintenance. Corrugated paper has limited potential as a component of ruminant diets; it is best used for maintenance of mature animals and probably should not exceed 25-30% of the diet.