Abstract
THE utilization of wood or bark as an energy source for ruminants has been tried on several occasions. 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 (Hvidsten and Homb, 1951; Nordfeldt, 1947). Most untreated woods are quite indigestible. Millett et al. (1970), using an in vitro rumen technique, found that of 24 species and subspecies examined, only aspen, ash and maple were digested to any extent. A recent study by Dinius et al. (1970) has confirmed that oak is essentially indigestible by sheep. The digestibility of some woods can be substantially increased, however, with appropriate chemical or physical treatment. Millett et al. (1970) used, with varying degrees of success, gamma irradiation, ammonia swelling, vibratory ball milling and dilute sodium hydroxide solutions to increase in vitro digestibility. Copyright © 1971. American Society of Animal Science . Copyright 1971 by American Society of Animal Science.