The Effects of Continuous and Rotational Livestock Grazing on Forb Quality and Quantity: Implications for Pronghorn Habitat Management

Abstract

Pronghorn (Antilocapra americana) evolved in grasslands with a diet composed of highly nutritious forbs. However, pronghorn habitat throughout North America has been lost to fragmentation and degradation. Additionally, the effects different cattle grazing regimes have on forb biomass, protein, and energy production for pronghorn are not well known in West Texas. We sampled forbs during the growing season in the months of September 2018 and 2019 to assess the effects of different cattle grazing regimes on forbs. We hypothesized rotational grazing would increase the nutritional quality of the forb community and overall forb production, compared to continuous grazing and no grazing. We randomly sampled pastures subject to continuous and rotational grazing, as well as ungrazed exclosures using 100, 96, and 64 1 m2 plots, respectively. We collected all forbs in each plot and analyzed differences in nutritional composition and biomass production using redundancy analysis. We found that the effects of grazing varied by year. In wetter conditions, rotational grazing exhibited higher forb quality and biomass, while exclusion from grazing exhibited these results under drier conditions. The knowledge gained from this study helps resource professionals and landowners understand how cattle grazing affects forbs for pronghorn. This knowledge may be used to improve the suitability of pronghorn habitat through cattle grazing regimes.