INTAKE AND NUTRITIVE-VALUE OF FLORIGRAZE RHIZOMA PEANUT SILAGE FOR LACTATING DAIRY-COWS

Florigraze rhizoma peanut (Arachis glabrata Benth.) is a very persiste nt, high quality legume that is well adapted to subtropical and tropic al environments. This legume was ensiled and compared with corn silage (Zea mays) as a feedstuff for lactating dairy cows. Twelve Holstein c ows, including 4 ruminally fistulated cows (mean, 70 days in milk), we re used in an experiment with a 4 x 4 Latin square design replicated t hree times. Diets were formulated to contain 50% concentrate on a dry matter (DM) basis. Dietary treatments were rhizoma peanut silage and c orn silage fed at DM ratios of 0:50, 20:30, 35:15, and 50:0. The dry m atter intake, digestibilities of DM and crude protein, and production of milk and fat-corrected milk decreased quadratically as the percenta ge of legume in the diet increased. Nearly all of the decrease occurre d when rhizoma peanut silage was the sole forage in the diet. The orga nic matter digestibility of the two forage types was similar; however, digestion of crude protein in rhizoma peanut silage was only 45% (cal culated using simultaneous equations). Ruminal pH increased, and ammon ia and total volatile fatty acid concentrations decreased, as the perc entage of rhizoma peanut silage in the diet increased. In situ digesti on rate constants for DM of rhizoma peanut silage were twice that of c orn silage, but extent of DM digestion was greater for corn silage. Pa ssage rates of concentrates and forage were unaffected by dietary trea tments. Rhizoma peanut silage can replace 70% of corn silage in diets containing 50% concentrate without affecting dairy cow performance.