Herbage Accumulation and Nutritive Value of Legume- or Grass-Based Forage Systems Defoliated By Grazing or Clipping.

Forage-livestock systems in the southeast US are primarily based on N-fertilized grasses. The inclusion of legumes offers the possibility of decreasing off-farm inputs and C footprint of livestock production and increasing forage nutritive value, but it may result in a reduction in herbage accumulation (HA) and livestock carrying capacity. The objective of this study was to determine HA and nutritive value (NV) of year-round (includes both warm- and cool-season forages) or warm-season only legume- and grass-based forage systems defoliated either by grazing or haying during two years. The eight treatments were two warm-season perennials, ‘Florigraze’ rhizoma peanut (RP, Arachis glabrata) and ‘Tifton-85’ bermudagrass (BG, Cynodon spp.), either overseeded in fall with cool-season forages or not overseeded, and defoliated either by grazing or clipping at 4- to 6-wk intervals depending on season. All overseeded plots were planted to rye (Secale cereale) and ryegrass (Lolium multiflorum) during winter, with the RP plots also overseeded to crimson (Trifolium incarnatum) and red clovers (T. pratense). Grass-N plots received 50 and 30 kg N ha^-1 after each summer and winter defoliation event, respectively. A double sampling technique was used to determine herbage mass before and after grazing events and to calculate HA on grazed treatments. The HA of clipped plots was determined using a sickle bar mower. Herbage for nutritive value analyses was collected prior each defoliation event to target grazing or clipping stubble and analyzed for N and in vitro digestible organic matter (IVDOM) concentrations. Results support the conclusion that defoliation management and species composition influence HA and NV.