Fiber separation from these animal feeds could increase the protein and hence increase the value of the animal feed. The objective of the study was to evaluate the combination of sieving and air classification for fiber separation from soybean meal (SBM), cottonseed meal (CSM) and wheat middlings (WM). The effect of yields of lighter fractions on fiber separation from size fractions was also investigated. At low yields of lighter fraction (5%), the quantity of fiber product separated was 3.7, 1.3 and 4.8% by weight of SBM, CSM and WM respectively. At high yields of lighter fractions (15%), the quantity of fiber product separated was 8.9, 3.5 and 11% by weight of SBM, CSM and WM respectively. For CSM and SBM, the enhanced product contained 0.6 to 2.0% higher protein content than unprocessed feed. For WM, the enhanced product contained 0.2 to 0.7% higher protein content than unprocessed feed.