A new methodology to measure internal particle size in pellets and to quantify the degree of grinding during pelleting
Type of DegreeMaster's Thesis
Restriction TypeAuburn University Users
MetadataShow full item record
Grinding and pelleting are the major costs during feed production. Previous research has shown that ingredients’ particle size can influence poultry performance, organ development, and nutrient digestibility. Particle agglomeration during pelleting improves feed handling, reduces wastage, increases feed intake, and improves broiler performance. However, the pelleting process leads to additional grinding, which results in inconclusive results regarding optimum particle size in broiler diets. Furthermore, the degree of grinding that occurs during pelleting is typically ignored or difficult to measure. In trial 1, a new methodology to evaluate the average particle size in the microstructure pellets after particle agglomeration and quantify the degree of grinding that occurs during the pelleting process was developed. Dietary treatments consisted of 3 corn particle sizes (801, 1,378, and 2,250 μm). A total of 24 meal and 12 pellet samples were collected at evenly spaced intervals from a 1-ton batch for each corn particle size. Twelve meal samples were analyzed as collected using the ASABE method S319.4 while 12 meal and 12 pellet samples were subjected to an additional procedure of hydration and dehydration using a novel methodology to separate agglomerated particles after pelleting. The objective of hydration and dehydration of meal diets prior to pelleting was to ensure the new methodology did not alter particle size or particle size distribution. The experiment consisted of a factorial arrangement of 3 corn particle sizes and 3 feed forms (meal, hydrated meal, and pellet). Data were statistically evaluated using the GLM procedure of JMP and means were separated by Tukey’s HSD with a statistical significance considered at P < 0.05. In diets with a corn particle size of 801 µm and 1,378 µm, meal and hydrated meal had higher (P < 0.05) particle size than the internal particle size within pellets (914 and 963 vs 716 µm; and 1,311 and 1352 vs 779 µm respectively). In diets with a corn particle size of 2,250 µm, hydrated meal had a higher (P < 0.05) particle size compared to the particle size within pellets (1,678 vs 1,085 µm) with the meal having an intermediate particle size of 1590 µm. A second trial was conducted to determine if the degree of grinding that occurs during pelleting was influenced by the initial corn particle size (855, 1,659, 2,043 and 2,534 m) and pellet diameter. Four meal samples produced from each corn particle size were collected for particle size analysis. Thereafter, meal diets were pellet through either a 3.0 or 4.0- mm pellet die. Pelleted samples were collected randomly from 4 bags during bagging and then subjected to a methodology developed in trial 1. The experiment consisted of 4 meal treatments (controls for each corn particle size) and a 2 x 4 factorial arrangement (2 pellet diameters x 4 particle sizes), totaling 12 treatments with 4 replicates per treatment. All the samples were analyzed using the ASABE method S319.4 with the addition of a sieving agent to prevent particle agglomeration during particle size analysis. Data were statistically evaluated using the GLM procedure of JMP and means they were separated by Tukey’s HSD with a statistical significance considered at P < 0.05. Pellet diameter did not influence the degree of grinding during pelleting (P > 0.05). As corn particle size increased, the particle size of the meal diets increased (936, 1,251, 1,387, and 1,567 µm; P < 0.05). The degree of grinding during pelleting increased as meal particle size increased regardless of the pellet die diameter (936 vs. 598 and 603 µm), (1,251 vs. 755 and 742 µm), (1,387 vs. 913 and 818 µm), (1,567 vs. 877 and 871 µm) when the initial corn particle size was 855, 1,659, 2,043, and 2,534 µm, respectively. The results of this study indicated that pellet diameter did not influence the degree of grinding during pelleting. However, as meal particle size increased, the degree of grinding during pelleting increased.