Characterization of forage weeds associated with grasslands under Voisin grazing system

Objective: To characterize forb and browse species associated to pastures that are forage for cattle, under Voisin grazing system Design/methodology/approach: Samplings were performed to build a floristic list at each of four sites: Pasture dominated by weeds (PasDomArv), secondary vegetation (VegSec), pasture invaded by weeds (PasInvArv), and a fallow field with woody vegetation (BarVegSec). The transition phase for the most abundant species at each paddock was set and the grow stage of each species was identified; plant selection was recorded by scan observation of 10 cows during active grazing. Crude protein (CP), neutral detergent fiber (NDF) and acid (ADF), lignin, total phenolics and tannins were performed on 18 species from all sites. Results: There were 65 species in the PasDomArv and Sida spinosa dominated, 51 species in BarVegSec and Solanum adscendens dominated, 51 species in Veg Sec and Cleome viscosa dominated, and 57 species in PasInvArv and Andropogon gayanus dominated. At the transition phase, most species were at vegetative stages and early blooming. Cattle diets was diverse, S. spinosa, Trianthema portulacastrum, Gonphrena globosa, Lagasea mollis and A. Gayanus were among those more chosen. Crude protein of forage plants ranged from 5.8 to 20.3%, NDF ranged from 31.5 to 72.9%, FDA ranged from 21.0 to 40.0%, lignin content reached up to 29.4%. Plants contained phenolic compounds (1.28-14.48%) and tannins (1.15-13.78%). Limitations on study/implications: It was an exploratory study. Findings/conclusions: Most forbs and browses associated to grazing sites, in differing grow stages, having different nutrient and phenolic compound concentration were used as forage by cattle, under Voisin grazing. Keywords: herbs, gramineous, chemical compositions, phenology