A technique involving the measurement of the gas production from the microbial fermentation of a specified substrate in sealed conditions has recently been proposed as a method of assessing the fermentation kinetics of tropical feeds (Theodorou et al, 1992). The objective of this work was to determine if such a technique could be used to assess the dry matter degradability of protein supplements.

1g air dried feed samples were placed with 95 ml of modified van Soest media and 5 ml of strained rumen liquor in 150 ml serum bottles and sealed under anaerobic conditions. Five replicates of soya bean meal (SBM), fish meal (FM), rape seed meal (RSM) and winter beans (WB) were set up together with control blanks that lacked the test feed. Bottles were incubated at 39.5°C for a 96 hour period and gas production volume measured at regular intervals. Cumulative gas production was corrected for the blanks and sample dry matter and plotted against time.