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Suboptimal brood-rearing habitat often limits sage-grouse (Centrocercus urophasianus) populations in western North America. In many mountain big sagebrush (Artemisia tridentata subsp. vaseyana) brood-rearing habitats, sagebrush canopy cover is too dense (> 25%) and limits the understory forbs that sage-grouse prefer to eat during summer. We investigated whether protein supplementation could concentrate cattle grazing or trampling during late fall to reduce mountain big sagebrush canopy cover and increase the diversity and abundance of forbs. We applied targeted cattle grazing within two large, contiguous pastures (approximately 615 ha each) in the Beaverhead Mountains of southwestern Montana. Pastures were grazed simultaneously at a light stocking rate (6.25 ha/AUM) for approximately two weeks in mid-October of 2015 and 2016. Within each pasture, we selected one 4-ha macroplot of dense sagebrush, and within each macroplot we treated and evaluated vegetation response at a spatial scale of 0.008 ha to match the spatial scale at which sage-grouse broods select habitat characteristics. We identified 16, 0.008-ha microsites where mountain big sagebrush canopy cover exceeded 30%. Each year we placed a low-moisture block protein supplement in the center of four microsites per macroplot, while another four microsites per macroplot comprised the untreated control. Vegetation response was quantified in early summer 2016 and 2017. One year after treatment, supplemented sites had 78% less sagebrush canopy cover (8% vs 36%), 31% more forb canopy cover (15% vs 12%), 19% greater forb diversity, and 13% greater forb richness than untreated sites (P ? 0.10). Bite count observations and fecal microhistology indicated that sagebrush cover was reduced by cattle trampling rather than browsing, as sagebrush comprised < 1% of cattle diets. Our results indicate that protein supplementation during late fall can concentrate cattle trampling sufficiently to enhance sage-grouse brood-rearing habitat.