QUANTITATIVE-EVALUATION OF FIBER FROM NONFORAGE SOURCES USED TO REPLACE ALFALFA SILAGE

The effectiveness of NDF from non-forage fiber sources was evaluated i n two trials using midlactation Holsteins. Dietary NDF was added to th e basal diet using either alfalfa silage or a nonforage high fiber fee d. Diets were fed for 21 d. In trial 1, four amounts of alfalfa were f ed. Basal milk fat percentage was 2.61 % at 144 g of alfalfa NDF/kg of diet and increased linearly by .066 for each additional 1% alfalfa ND F added, up to 22.8 g of alfalfa NDF/kg of diet. Based on one amount o f added nonforage fiber, the ratio of fat test increase to NDF added w as .014 for brewers grains, .040 for oat hulls, and .047 for com glute n feed. In trial 2, one amount of added alfalfa and each nonforage fib er source was used. The ratio of fat test increase to added NDF was .0 94 for alfalfa, .043 for brewers grains, .067 for oat hulls, .038 for com gluten feed, .041 for beet pulp, and .044 for malt sprouts. When a dded to low fiber diets, NDF from the non-forage fiber sources elevate d milk fat concentration approximately one-half as effectively as did NDF from alfalfa. Chewing activity was less affected by nonforage NDF than was milk fat concentration.