Determination of particle size of pig diets containing 20% air-classified pea starch before and after pelleting

Particle size (PS) reduction can improve animal performance but may contribute to gastric ulcers. Fine ingredients such as industry-available by-product air-classified pea starch (ACPS) or pelleting may reduce PS. Dry sieving is the most commonly used particle size analysis (PSA) for feed, but laser diffraction is used in food applications and may be more accurate. The objective of this study was to determine if wet laser diffraction is more effective than dry sieving PSA method when the diet contains ACPS or is pelleted. Treatments included 2 ACPS inclusion levels (0 or 20%) and 2 feed forms (mash or pellet), analyzed by dry sieving or wet laser diffraction. Pellets were ground using a spice grinder for 10 seconds prior to dry sieve method or soaked in water for 5 minutes and passed through a 2 mm sieve prior to wet laser diffraction. ACPS inclusion (0 vs 20%) reduced PS in mash diets (520 to 458 and 729 to 637 μm, dry sieving vs laser diffraction, respectively. Pelleting reduced PS of diets without ACPS (520 to 421 and 729 to 419 μm, dry sieving vs laser diffraction, respectively). The addition of ACPS to pelleted diets did not affect PS. It was concluded that dry sieving method reported more consistent results but lower PS than the laser method. Diet PS was lower with the addition of ACPS in mash, but not pelleted diets. Pelleting significantly reduces particle size, therefore it is recommended that particle size should be measured post-pelleting.

Presented at the 2024 Animal Nutrition Conference of Canada. For information on the next edition, click here.