INFLUENCE OF PARTICLE-SIZE ON THE EFFECTIVENESS OF BEET PULP FIBER

Sixteen Holstein cows in midlactation were used in a design based on a replicated 4 x 4 Latin square with the last period removed to determi ne the influence of particle size of beet pulp neutral detergent fiber (NDF) on its effectiveness as a replacement for alfalfa NDF. Diets we re a low forage, low fiber diet [12.1 g of alfalfa NDF/100 g of dry ma tter (DM)], a normal forage diet (low forage plus 7.8 g of additional alfalfa NDF/100 g of DM), and two low forage diets with 5.3 g of NDF/1 00 g of DM from either whole or finely ground dried sugar beet pulp. R eplacement of alfalfa fiber with beet pulp fiber increased milk protei n yield because of the tendencies toward increased milk yield and prot ein concentration. However, milk fat concentration and yield were unaf fected. The addition of beet pulp fiber, either whole or ground, to th e basal low forage, low fiber diet did not affect yields of milk, prot ein, or fat, but milk protein concentration tended to be lower for cow s fed the beet pulp diets than for cows fed the basal diet. Reducing t he particle size of beet pulp increased DM intake but did not affect a ny of the milk yield measurements. Particle size reduction of beet pul p did not reduce its effectiveness as a fiber source as measured by ch anges in milk fat content.