Studies were made of particle size distribution in meals produced from typical ingredients used in pig diets and of dietaries formulated from such ingredients. Each meal was subjected to a sieving procedure through standard sieves and the fractions retained by the sieves were weighed. The modes of expressing the results included moduli of fineness and uniformity and cumulative totals of oversize material, the latter forming the basis of the system preferred. Preliminary investigations into factors of loading weight, time of shaking and reproducibility of results led to the ultimate adoption of a standard technique of mechanical shaking of 100 g loads for 10 min. The technique was used to study particle size distribution in various cereals, cereal by-products, animal and vegetable protein sources and mineral mixtures employed in pig dietary formulations. The studies also included the particle distribution pattern in barley milled at varying grist sizes and in replicated samples of a commercial pig meal.

The suggested technique of characterizing particle size distribution should materially assist investigations into problems of pig health and productivity that appear to be associated with grist size of dietary meals.