Investigating the effect of pelleting on the particle size of commercial poultry feeds: a case study

Abstract

SUMMARY: A study was conducted to investigate the effect of pelleting on the particle size of commercial poultry feeds. A total of 38 feed samples each in mash and pellets were collected from commercial poultry feed mills and analyzed for particle size determined as geometric mean diameter (GMD). Mash samples were dry sieved while pellets were wet sieved. The results showed that mash GMD significantly reduced (P < 0.001) from 802.0 to 544.3 µm when the samples were pelleted, whereas the geometric standard deviation (GSD) was increased (P = 0.037) from 2.029 to 2.135 µm. The calculated minimum GMD, maximum GMD, and GMD range of pelleted feeds were significantly reduced (P < 0.001) compared with mash feeds. Pelleting did not affect (P = 0.242) particles larger than 4.0 mm. However, particles in size 0.5 to 4.0 mm were significantly reduced (P < 0.001) in quantity, whereas particles smaller than 0.5 mm were significantly increased (P < 0.001) in pellets. A strong Pearson's correlation (R2 = 0.659) was observed between mash GMD and the reciprocal of pellet GMD. To predict pellet GMD, the validation results of the models produced showed that a linear model can be used to estimate pellet GMD as a function of mash GMD efficaciously with the least change in R2 and predictability error compared with bivariate polynomial fit models with degrees 2 to 4. For wheat-soy-based commercial feeds, the particle size (GMD) is reduced by about 32% when the mash is pelleted and the GMD of pellets can be predicted with reasonable confidence from a measure of mash feed GMD.

Keywords

• poultry feed
• pelleting
• particle size
• modeling
• estimation