Steer diets in a montane riparian community

Abstract

Diets of fistulated steers that grazed a montane riparian community were determined throughout a growing season. The objective was to determine if willow (Salir spp.) consumption by steers was related to the season of use and the residual stubble heights of herbaceous forae species. Diet samples were collected at 4 levels of herbaceous utilization throughout 4 grazing periods that were based on willow phenology. Results suggested that spring grazing of riparian pastures was preferable to late-season use to minimize browsing on willows. Willow consumption increased substantially as herbaceous stubble height approached 10 and 18 cm during the spring and early- summer grazing periods, repectively. Stubble heights greater than 20 cm were needed to reduce willow consumption when they were most preferred during the late- summer and fall grazing seasons in this tall sedge (Carex spp.)/willow riparian community. Sedge and rush (Juncus spp.) composition in steer diets declined, while willow composition increased in steer diets, in response to decreasing stubble heights. Grass consumption by steers was little affected by stubble height, while forb consumption was directly related to forb availability. Although grazing activity has the potential to negatively impact riparian willows, these results suggested that timing of use and carefully controlled levels of herbaceous utilization could be used to minimize the consumption of willows by cattle in a montane riparian community.