NONDESTRUCTIVE MEASUREMENTS OF CANOPY VOLUME TO ESTIMATE GRAZING ACTIVITY

Assessing livestock preference for entries of forage breeding programs is important because livestock defoliate plants discriminantly, and t hus influence plant competition and survival. We compared seven non-de structive methods for evaluating tall fescue (Festuca arundinacea Schr eb.) defoliation. Cross-section, height, and spread measurements from a grid; hemisphere, cube, and cylinder formulae applied to height and diameter; and settling plate measurements were regressed against non-s ubjective determinations using a plane table. The hemisphere equation applied to height and diameter assessed defoliation best. Coefficients of determination ranged from 0.07 to 0.85 for the plate method and he misphere formula respectively. Our results reflect vegetative plants. Other methods may be better for taller plants.