Alfalfa or orchardgrass hay was fed to cattle before feeding fresh alfalfa herbage at the vegetative to early bud stage of growth to observe the subsequent impact on bloat. Alfalfa hay supplements reduced the incidence of bloat by a third in one trial, but no effect was seen in a second trial. In contrast, supplements of orchardgrass hay reduced the occurrence of bloat by > 90% in 2 yr of trials. Supplemental orchardgrass hay can be effective in the control of pasture bloat. Key words: Steers, frothy bloat, Medicago sativa L., Dactylis glomerata L., hay supplements