Influence of diet pellet hardness and particle size on food utilization by mice, rats and hamsters.

Increasing hardness of diet pellets reduced food wastage by each species. Also, less wastage occurred when pellets made from finely ground materials were given, an effect that was not related to hardness. The hardest diet reduced growth of the mice by reducing true food consumption and a poorer food conversion efficiency (true food consumption/growth) was obtained. Apparent food consumption increased with the softness of the diet and food utilization (apparent food consumption/growth) of the softest diets was less efficient than those of the others. Grinding of the raw materials prior to pelleting had no effect on food conversion, but food utilization was less efficient because of the greater wastage of pellets from coarsely ground materials and consequent apparent food comsumption.