The use of cumulative gas production to determine the effect of steam explosion on the fermentability of two substrates with different cell wall quality

Abstract

Wheat straw, ammoniated wheat straw and corn silage, were treated under constant conditions of steam explosion, differing only in the time for which the material was subjected to steam, prior to discharge from the vessel. The three feedstuffs were evaluated for their fermentability 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 test). 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 time of steaming, which tended to be negative in the case of straw. A significant interaction was found between type of substrate and duration of steam injection. The results suggest that steam explosion, under these conditions, was not a practical approach as a pretreatment for animal feed particularly of poor quality cell walls such as those from wheat straw.