Pulp and Papermaking Residues as Feedstuffs for Ruminants

Summary N a search for a more productive outlet I for the fibrous residues generated during commercial pulp and paper operations, repre­ sentative residues were screened for their potential as feedstuffs for ruminants, In vitro rumen digestibilities of many of the residues ranged from 45 to 60% ; some attained levels as high as 90%. Analytical data for Klason lignin, total carbohydrate, and ash constituents were also obtained. Four typical residues-screen rejects from the sulfite pulping of aspen, unbleached paren­ chyma cell fines from an aspen sulfite tissue mill, unbleached fines from a southern pine kraft mill, and bleached fines from a mixed hardwood southern kraft mill-wereobtained in sufficient quantity for feeding trials with goats, sheep, and steers. The residues were blended with other ration ingredients, and pelleted. In vivo digestibilities for the four residues are estimated to be 58, 52, 47 and 78%, respectively, indicative of substantial utilization of the available carbohydrate con­ stituents. A ration containing 77.4% paren­ chyma cell fines adequately maintained ewes for 2.5 months, and had good acceptability. Steers were fed rations containing 0 and 50% unbleached southern pine kraft pulp fines ad libitum for 58 days. Average daily gain was 0.77 and 0.54 kg, daily feed intake as a percent of body weight was 2.84 and 2.48, and feed/gain ratio was 9.44 and 11.69 for the 0 and 50% pulp rations, respectively. Rumen pH, ammonia, and volatile fatty acid ranged from 6.4 (0 pulp ration) to 6.6 (65% 1