DINAMICS OF RYEGRASS AND TALL FESCUE ASSOCIATION SUBMITED TO ANIMAL DEFOLIATION

Abstract

The experiments was carried in INRA (Institut National de La Recherche Agronomique) at Theix, France. Two grasses (perennial ryegrass and tall fescue) were grown in sward boxes (0,13 m2), using three different sward horizontal distribution (pure, alternate rows and alternate strips) and three defoliation frequencies (3, 5, 7 and 14 days between two successive defoliation) with four replications. Four months after sowing, at defoliation date, sward boxes were offered to four individual dry ewes and removed after 340 bite.m-2 had been made. For each grass species, the density and the tiller mass, the sward height, the production of mass, the bite depth and the bite mass and growth, senescence and defolation fluxes were studie. The largest height of the sward, generated by less frequent defoliation, promoted the accomplishment of deeper bites and of larger mass. On the other hand, in more frequent defoliation, the height of the sward was maintained lower, and the depth and mass of bites were smaller. The horizontal distribution of the sward promoted differentiated responses in relation to the growth, senescene and defoliation fluxes. When in alternate rows, the tall fescue probably had the growth flux limited unfavorable by the competition.