Applied Engineering in Agriculture Vol. 38(5): 777-785 2022 American Society of Agricultural and Biological Engineers ISSN 0883-8542 https://doi.org/10.13031/aea.14845 777 POTENTIAL OF DIMENSIONAL MEASUREMENTS OF INDIVIDUAL PELLETS FOR EVALUATING FEED PELLET QUALITY Lester O. Pordesimo 1,* , C. Igathinathane 2 , Basil D. Bevans 3 , David P. Holzgraefe 3 1 Stored Products Insect and Engineering Research Unit, USDA ARS Center for Grain and Animal Health Research, Manhattan, Kansas, USA. 2 Department of Agricultural and Biosystems Engineering, North Dakota State University, Fargo, North Dakota, USA. 3 ADM Animal Nutrition, Quincy, Illinois, USA. * Correspondence: lester.pordesimo@usda.gov HIGHLIGHTS  Pellet length but not width increased significantly with increasing inclusion of a pellet binder in a pelleted feed  Machine vision capably and rapidly measures pellet length  The narrow range in pellet length measurements prevents its use as an effective discriminator of pellet quality  Pellet durability index from aggressive pellet durability testing is the better discriminator of feed pellet quality ABSTRACT. Pellet durability index (PDI) detailed in ASAE Standard S269.4 (ASAE Standards, 2007) has been the widely accepted measure for pellet quality in the U.S. and, by extension, the measure for evaluating the effect of ingredients and pelleting process variables on the quality of pelleted feed products. The PDI is calculated as the mass percentage of intact pellets remaining after tumbling a 500 g sample in a tumbling can durability tester for 10 min. In the case where pellet quality is good, oftentimes the resulting PDI for different experimental treatments are very close in magnitude. In these situations, it is desirable to have another measurement that would allow for finer discrimination among treatments. It was hypothesized that the average linear dimensions of animal feed pellets in a unit mass sample would vary as a function of formulation and pelleting process variables for a consistent knife setting in the pellet mill. This hypothesis was tested in a study involving effectiveness testing of varying inclusion levels of a potential pellet binder in a typical corn-soy swine diet pelleted by both conventional and cold pelleting processes. Pellet lengths and diameters measured by a machine vision implemented in ImageJ matched to measurements taken manually and varied with treatments. Pellet length varied with treatments but could not be a good discriminator of pellet durability between pelleted products because of the narrow range in measurement numbers (8.53 to 11.15 mm by machine vision). With the wider range in numerical values of the PDIs obtained through aggressive durability testing (23.0% to 81.0% in a tumble can with steel hexagonal screw nuts versus 91.0% to 97.5% in a tumble can without hexagonal nuts), PDI from aggressive testing is the better discriminator of quality among pelleted products because of its greater resolution. Keywords. Animal feed, Durability, Linear dimensions, Machine vision, Pellet, Pellet binder, Pelleting, Quality. n the animal feed manufacturing industry, the pelleting process provides a means of molding a blend of ground nutritional ingredients into dense free-flowing agglom- erates known as pellets (Behnke, 2009). Pelleting is ac- complished through a mechanical process combining moisture, heat, and pressure. The benefits of pelleting in- clude enhanced handling characteristics of feeds (increased bulk density and flowability, and reduced ingredient segre- gation), improved feed efficiencies, and destruction of some deleterious organisms (Behnke, 2001; Fairfield, 2005). Rec- ognizing the former two benefits in particular, livestock and poultry producers and those others raising animals and poul- try have come to expect better quality in the pelleted prod- ucts they produce or purchase. Justifiably so because feed is the largest single cost item for livestock and poultry produc- tion, accounting for 60% to 70% of the total cost in most years (Lawrence et al., 2008). For producers, the quick indi- cator of pellet quality is the absence of an inordinate amount of fines in the product. In 2019, the quantity of feed fed to beef cattle, hogs, broilers, dairy cattle, egg layers, and tur- keys in the U.S. was 241.9 MT (Decision Innovation Solu- tions, 2020). Based on research on the effect of feed form on The authors have paid for open access for this article. This work is licensed under a Creative Commons Attribution- NonCommercial-NoDerivatives 4.0 International License https://creative commons.org/licenses/by-nc-nd/4.0/ Submitted for review on 9 September 2021 as manuscript number PRS 14845; approved for publication as a Research Article by Associate Editor Dr. Ajay Kumar and Community Editor Dr. Sudhagar Mani of the Processing Systems Community of ASABE on 2 August 2022. USDA, NDSU, and ADM are equal opportunity providers and employers. The mention of trade names of commercial products in this article is solely for the purpose of providing factual information and does not imply recommendation or endorsement by the aforementioned organi- zations. I