ABSTRACT
The annual timber harvest in the US is in excess of 200 million tons. The advent of high energy prices has made the use of wood as a fuel within the wood processing industries more attractive, and the potential supply of underutilized wood residues may be reduced from amounts prevailing in the early 1970s. In the Scandinavian countries more than 1.5 million tons of sulfate and sulfite pulps from spruce, pine, and fir were fed to cattle and horses during World War II when feed supplies were short. Lignin is generally recognized as being responsible for the low digestibility of wood. With a lignin content of 20 to 30%, wood contains about twice as much lignin as most forages. In 1943, at the request of the War Production Board, the Forest Products Laboratory reexamined dilute sulfuric acid hydrolysis of wood residue material. Of the many chemical and physical pretreatments explored thus far, delignification is by far the most universally applicable.
