The Effects of Hammer Mill Screen Size on Ground Corn Particle Size, Pellet Durability, and Broiler Performance

Abstract

Corn ground by a hammer mill, with screens ranging from 3.18 mm (.125 in) to 9.53 mm (.375 in), was used to formulate pelleted broiler diets that were fed to broilers grown in a moderate (21- to 24-C) environment. Corn ground with either a 3.18-mm or a 9.53-mm mill screen produced significantly better weight gains and feed conversions than corn ground with a 6.35-mm screen. Geometric mean diameter of the ground corn was found to vary linearly with the diameter of the opening in the hammer mill screen used for grinding. Pellets made from corn ground with the 9.5 3-mm screen were significantly more durable than those made from the finer ground corn. These results indicate, contrary to popular beliefs, that grinding corn to the same fineness as the other ingredients in a diet to be pelleted does not result in improved broiler performance or improved pellet durability. Substantial reduction in energy for grinding would result from using a mill screen with larger openings than commonly used.