Effect of aqueous ammonia and other alkalis on the in‐vitro digestibility of barley straw

Abstract

Abstract The in‐vitro digestibility of the organic matter of unground barley straw was increased by approximately 14 units by treatment with aqueous ammonia for 1 week at 20°C. Longer treatment times of 4 and 13 weeks had little or no additional effect on digestibility. Treatment with sodium hydroxide or tetramethylammonium hydroxide increased digestibility by up to 22 units. The content of cell walls of the straw after treatment with any of the alkalis was lower than that of untreated straw and the degradability of the walls from alkali‐treated straw was more than 85% greater than that of the walls from untreated straw. Alkali treatment of straw caused loss of p ‐coumaric, ferulic and diferulic acids from the cell walls, the loss being greater with the stronger alkalis. The loss of ferulic was greater than that of p ‐coumaric acid.