We tend to obsess over protein levels and amino acid specifications in soybean meal, but we rarely stop to ask, "How fine is it ground?" For something that makes up one-quarter or more of many broiler feeds, particle size still hides in the background, yet it quietly affects how the bird digests everything else.
When soybean meal is ground too fine, it slips through the upper digestive tract too quickly. The gizzard barely gets to work. What you gain in pellet uniformity, you lose in gut stimulation. On the other hand, coarser particles make the gizzard earn its keep — contracting harder, holding feed longer and priming it for enzymatic digestion downstream. Studies have shown that birds fed coarser soybean meal end up with heavier gizzards, better feed efficiency and, in some cases, even improved carcass yield (Amerah et al., 2013; Svihus, 2011).
