EFFECT OF YEAST ON FEED-INTAKE AND PERFORMANCE OF COWS FED DIETS BASED ON CORN-SILAGE DURING EARLY LACTATION

Thirty-six multiparous Holstein cows were fed a mixture of corn silage and concentrate [1:1; dry matter (DM) basis] and long hay (0.9 kg/d) through wk 18 of lactation. Beginning at 30 d prepartum through wk 4 o f lactation, the total mixed rations of 18 of these cows were top-dres sed daily with 10 g of Biomate(R) Yeast Plus(R) (Chr. Hansen's, Inc., Milwaukee, WI). The other 18 cows served as controls. At wk 5, bath co ntrol and treated cows were divided into three groups and fed 0, 10, o r 20 g/d of yeast. Yeast supplementation during early lactation signif icantly improved DM: intake, milk yield, and the digestibility of crud e protein and acid detergent fiber. Least squares means for DM intake, fat-corrected milk yield, crude protein digestibility, and acid deter gent fiber digestibility for cows fed 0, 10, 20 g/d of yeast during wk 5 to 18 of lactation were 23.8, 24.7, and 25.0 kg/d; 37.7, 40.7, and 41.4 kg/d; 78.5, 80.8, and 19.5%; and 54.4, 60.2, and 56.8%, respectiv ely. Although numerical responses in DM intake and milk yield were gre ater for cows fed 20 g/d of yeast than for cows fed 10 g/d of yeast, t he response was not significant.