Freshly pressed and dried sugar beet pulp was sampled from 2 different factories located within a distance of 30 km and on 4 different dates. One factory was equipped with a steam dryer and the other with a drum dryer. A recognized in vitro technique was used to establish, how the drying process affected rumen fermentability of the pulp, since fibrous feeds (such as sugar beet pulp) rely on microbial fermentation in the rumen to be digestible to the cow. Steam dried pulp had a remarkable >60% higher fermentability compared to drum dried pulp during the first 12(-15) hours of fermentation, but there were no differences in fermentation pattern after 24 hours of fermentation. The increased early fermentability must markedly increase the nutritional value for high-yielding dairy cows, which at feed intakes of 25 kg dry matter or more, have retention times in the rumen for water soluble compounds (such as pectin) and small particles as low as 6.7-13.3 hours. Future feeding trials are needed to establish exactly how much the feeding value is increased in steam dried sugar beet pulp.