This study of forage nutritive value was conducted on irrigated pasture species in the Intermountain West over a period of four years. Grasses or binary grass-legume mixtures were clipped and fertilized at each cutting to simulate rotationally stocked pastures. The grass species evaluated were an early and a late diploid perennial ryegrass (PRG), along with orchardgrass (OG), tall fescue (TF), meadow brome (MB), and a pasture-type Kentucky bluegrass (KBG). Grasses were seeded with alfalfa (ALF), birdsfoot trefoil (BFT), cicer milkvetch (CM) or white clover (WC). Grass monocultures and mixtures were either allowed to reach grass early heading stage before the first cutting or were clipped to simulate rotational stocking management all season long. We will report on the seasonal distribution of in vitro dry matter digestibility.