Recent research in our laboratory demonstrated that average particle size of feed from 0 to 14 d influenced overall (0 to 46 d) performance. However, optimal starter average feed particle size has not been identified and represents an important void, as this is a critical stage in a broiler's lifecycle. Therefore, 2 experiments were conducted to evaluate the effects of average particle size on 0 to 14 d broiler performance in an effort to determine the optimal average particle size. Both experiments utilized Ross × Ross 708 male broiler chicks that were provided diets varying in average feed particle size from 1,202 to 2,172 μm (Experiment 1) or 1,174 to 3,736 μm (Experiment 2). Performance variables were analyzed with a randomized complete block design using one-way ANOVA. Improvements were most apparent for FCR with an associated 0.03 improvement in both experiments when broilers were provided feed of 1,760 or 2,172 μm (Experiment 1) or larger than 2,257 μm, compared to those receiving smaller average feed particle sizes (Experiment 2). Additionally, a 30 g improvement for ending BW and BW gain was demonstrated in Experiment 2 for broilers receiving ≥2,800 μm. However, linear relationships for 0 to 14 d FCR, ending BW, and BW gain for Experiments 1 and 2 demonstrate that the optimal particle size may not have been achieved during these experiments. Therefore, future research should focus on further expanding the range of particle sizes tested (beyond 3,700 μm) from 0 to 14 d to identify the optimal average feed particle size during this growth phase.

SUMMARY Previous research has focused on providing improved feed form (FF) in the finishing growth phase of broilers (>28 d) to optimize performance. However, it may be more economical to improve FF in earlier growth phases (