Hammermill screen selection for soybean processing: effects of soybean meal particle size on amino acid digestibility, feed milling efficiency, and D1-42 broiler performance

Corn particle size (PS) affects feed milling parameters, amino acid (AA) digestibility, and broiler performance. However, there is limited work on soybean meal (SBM) PS. Three experiments were conducted to determine the effects of SBM PS on d21 apparent ileal AA digestibility (AIAAD), feed milling efficiency, pellet quality (PQ), and d1 to 42 broiler performance. A hammermill fitted with one of three screens (2.4-mm, 5.6-mm, 7.9-mm) was used to process the SBM used in all experiments. In experiment 1, an indigestible marker, titanium dioxide, was added to the diet and its concentration in digesta was used to calculate AIAAD. D 21 AIAAD was influenced by SBM PS where fine SBM (2.4 mm-screen) reduced AA digestibility for all AA compared to other treatments (P < 0.05). In experiment 2, SBM PS did not affect hot pellet temperature or production rate (P > 0.05). However, PQ improvements were apparent when the fine SBM was used (P < 0.05). In experiment 3, SBM PS impacted broiler performance in all feeding phases (P < 0.05). Overall (d1–42) FI, BWG, and FCR increased when fine SBM was fed compared to when medium (5.6-mm screen) and coarse (7.9 mm-screen) SBM was fed (P < 0.05). Finally, SBM PS did not affect gizzard size (P > 0.05). These experiments suggest that although finely ground SBM improves PQ between 5 and 8%, the fine SBM PS reduces AIAAD and worsens broiler FCR.