THE USE OF CUMULATIVE GAS-PRODUCTION TO DETERMINE THE EFFECT OF STEAMEXPLOSION ON THE FERMENTABILITY OF 2 SUBSTRATES WITH DIFFERENT CELL-WALL QUALITY

Wheat straw, ammoniated wheat straw and corn silage, were treated unde r constant conditions of steam explosion, differing only in the time f or which the material was subjected to steam, prior to discharge from the vessel. The three feedstuffs were evaluated for their fermentabili ty by measurement of cumulative gas production with time. Fermentation curves were fitted to a model and the resultant parameters tested for significant differences by an analysis of variance (using the Tukey t est). Neutral detergent fibre and neutral detergent insoluble nitrogen were analysed before and after both steam treatment and fermentation. The substrates were significantly different from each other in terms of gas production parameters. Generally, there was an effect of the ti me of steaming, which tended to be negative in the case of straw. A si gnificant interaction was found between type of substrate and duration of steam injection. The results suggest that steam explosion, under t hese conditions, was not a practical approach as a pretreatment for an imal feed particularly of poor quality cell walls such as those from w heat straw.