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3. Forest Residues
Pages 69-120

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From page 69...
... WHOLE-TREE RESIDUE AND FRACTIONS OF WHOLE TREES Quantity Historically there has been little need for forest inventory information on quantities of forest biomass beyond information on raw material needed by the forest products industry. As a result, inventories estimated the volume of forest biomass as merchantable boles of commercially important tree species measured from a minimum of 13 cm diameter at breast height 69
From page 70...
... The estimates of annual forest biomass potential are shown in Table 7. In addition, the report indicates that if 10 percent of the arable land that is currently private forest, pasture, range, and hay land were used for intensive production, up to 240 million dry tons additional annual forest biomass production could be available.
From page 71...
... Collectibility Not all of the annual forest biomass potential shown in Table 7 is collectible. Some will be on lands where it is too costly to harvest because of terrain or distance from markets.
From page 72...
... Although limited quantities of forest biomass will be available in the future from primary and secondary wood processing plants, biomass availability for livestock feed will most likely be obtained directly from the forest. This material could be a by-product of the system for the harvesting of whole-tree pulp or fuel chips.
From page 73...
... This can usually be done quite economically with a hammermill. Forest residues include treetops, branches, and short lengths of logs.
From page 74...
... Storing fresh bark, whole-tree chips, and foliage is more difficult than storing wood in the form of sawdust, chips, and shavings because of the higher amount of nutrients and biologically active materials. Nutritive Value Most untreated woods are quite indigestible.
From page 75...
... 37 Bigtooth aspen 31 Black ash 17 45 American basswood 5 25 Yellow birch 6 16 White birch ~ Eastern cottonwood 4 American elm 8 27 Sweetgum 2 Shagbark hickory 5 Soft maple 20 Soft maple buds 36 Soft maple small twigs 37 Sugar maple 7 14 Red oak 3 White oak 4 Softwoods Douglas fir 5 Western hemlock 0 Western larch 3 7 Lodgepole pine 0 Ponderosa pine 4 Slash pine 0 Redwood 3 Sitka spruce 1 White spruce 0 a96-hour in vitro rumen digestibility. For comparison, the 96-hour digestibility of cotton liners was 90 percent and of a reference alfalfa, 61 percent.
From page 76...
... Crude protein content of aspen bark is usually less than 3 percent on a dry basis. From 5 to 10 percentile ether-extractable.
From page 77...
... Wethers receiving diets containing 37 and 53 percent aspen bark gained approximately 0.04 kg/day during the 48-day trial. Wethers receiving the 68 percent bark diet lost about 0.04 kg/day.
From page 78...
... Dry-matter digestibility of the sawdust portion of the diet was 41 percent when it was incorporated into a high-roughage diet and 28 percent in a high-concentrate diet. Whole Aspen Tree Chemical Composition As with other wood residues, crude protein content of whole-aspen-tree material is very low (see the section, "Forest
From page 79...
... reported dry-matter digestibilities of 51, 52, 54, 60, and 63 percent for total mixed diets containing 0, 12, 24, 36, or 48 percent ground whole aspen tree. Animal Performance A series of three experiments involving rather large numbers of cattle fed whole-tree material have been reported from South Dakota.
From page 80...
... a diet of 48 percent aspen, 13 percent alfalfa, and 32 percent soybean meal; and (6) a diet of 48 percent aspen, 13 percent alfalfa, 16 percent soybean meal, and 16 percent chicken manure.
From page 81...
... A top dressing of soybean meal at the rate of 1 .2 kg/head/day was offered starting December 15 to increase the crude protein content of the silage diet to 7 percent. Soybean meal supplementation was increased to 1.7 kg per head per day from January 27 until termination of the experiment.
From page 82...
... has estimated that the foliage in the world's forests could produce more than lOO million tons of muka. A conservative estimate of foliage practically available would yield somewhat less, perhaps 10 million tons.
From page 83...
... . Chemical Composition The chemical composition of muka varies with the species of tree used, but the values given in Table 13 may be considered characteristic of commercial muka from Pinus sylvestris.
From page 84...
... Two plants used dilute sulfuric acid hydrolysis, with the major product being ethyl alcohol, and the other plant used anhydrous sulfur dioxide gas and produced feed (Kressman, 19221. Research to utilize wood in animal feeds began at the Forest Products Laboratory in 1920 when eastern white pine (Pinus strobus)
From page 85...
... Results indicated that certain animals could eat diets containing up to one-third hydrolyzed sawdust mixture. Animals such as dairy cows requiring considerable energy intake could eat up to 15 percent of the hydrolyzed mixture without noticeable effects on milk production.
From page 86...
... The other plant uses a steam-pressurized refiner to defibrate the wood chips. In each plant the solubilized wood materials, which are mainly hemicellulose sugars and organic acids, are neutralized and either concentrated or spray dried for use in animal diets.
From page 87...
... Without the alkali treatment, the maximum attainable digestion was only a few percent. Data are presented relative to the in vitro digestibility and lignin content of some typical hardwood species treated with 1 percent sodium hydroxide at a 20:1 solution-to-wood ratio (see Table 14~.
From page 88...
... . No uniformity exists in the response of the various species to sodium hydroxide treatment.
From page 89...
... (1970) investigated the influence of alkali concentration on the extent of in vitro digestion of aspen and red oak (Quercus rubra)
From page 90...
... Extrapolation of the curves to 100 percent aspen yielded dry-matter digestibilities of about 41 percent for untreated aspen and 52 percent for the alkali-treated aspen. - Alkali treatments can thus increase ruminant utilization of aspen wood by approximately 25 percent, making it equivalent to a medium-quality hay as a source of dietary energy.
From page 91...
... (Carr.~) and red oak (Quercus rubra)
From page 92...
... That it can be is indicated by the more than 1.5 million tons of sulfate and sulfite wood pulps from pine, spruce, and fir consumed by cows and horses during World War II in the Scandinavian countries (Edin, 1940; Edin et al., 1941; Hvidsten, 1940; Nordfeldt, 1951; Saarinen et al., 19581. This was an emergency situation,
From page 93...
... o: 40 20 I' / , / ' o PAPER BIRCH o ~, BRED OAK / ~ _ - o ~ _~' /~/ / ~ ~' / /1 ~ - ~ / ,' /o / to' to At' ' RED PINE/ ~ // Ill l/l /// / l '' DOUGLAS FIR O. 20 40 60 EXTENT OF DELIGNIFICATION ( % ) FIGURE 6 Relationship between in vitro digestibility and extent of delignification for kraft pulps made from four wood species.
From page 94...
... Following this lag phase, digestibility rises rapidly and almost linearly with delignification up to the digestibility maximum. As interpolated from these four curves, the extent of delignification necessary to obtain a product having an in vitro digestibility of 60 percent, that of a good-quality hay, is shown in Table 15 along with data on the lignin content of the original woods.
From page 95...
... As determined by the protein content of the fungal mass, reasonable growth on hardwood could be obtained at lignin contents of 14 percent or less, whereas fungal growth on softwoods was restricted to pulps having less than 3 percent residual .
From page 96...
... Wood Before After Before After Before After Quaking aspen 20 7 70 71 9 63 Yellow birch 23 9 66 67 4 65 Sweetgum 20 5 66 64 2 67 Red oak 26 8 62 60 1 60 Douglas fir 30 24 65 63 0 46 Ponderosa pine 31 19 59 58 0 50 Alfalfa 17 51 25 SOURCE: Baker et al.
From page 97...
... From the shallow slope of the curves, it appears that a vapor-phase treatment with sulfur dioxide effectively converts red oak sawdust into a ruminant feedstuff having the dietary energy equivalence of a medium-quality forage. Neutralization of the treated product with ammonia rather than sodium hydroxide would augment its crude protein content.
From page 98...
... There is a very high inverse correlation between lignin content of the decayed wood and in vitro rumen digestibility. The coefficient of correlation is 0.95 for aspen and 0.97 for birch.
From page 99...
... The digestion of aspen carbohydrates is essentially quantitative after an electron dosage of 108 red, while spruce is only 14 percent digestible at this dosage.
From page 100...
... . Utilization Systems Experimental Previous research has demonstrated that certain fractions of forest biomass can be made useful in animal diets without additional treatments.
From page 101...
... By choosing proper growing, harvesting, and processing methods, forest biomass can be wisely used for traditional forest products, fuel, and livestock feed. PULPMILL AND PAPERMILL RESIDUES Quantity The quantity, location, and composition of pulpmill and papermill primary sludges have been reported by Joyce et al.
From page 102...
... The quantity and quality of the primary sludge are site-specific, and complete nutritional and chemical analyses are required to determine the usefulness of a sludge in animal diets. For use in animal diets, the fibers should be collected prior to entry into the primary collection site.
From page 103...
... production rate of nearly 52 x 106 tons/year, 2.2 x 106 tons/year of cellulosic fibers are available in the primary sludge. North American sulfite pulp production and estimated associated sulfite spent liquor (SSL)
From page 104...
... TABLE 22 Kilograms Primary Sludge Produced per 1000 Kilograms Paper Production, by Region Sludge Production Mills Regiona Reporting Average Minimum Maximum 1 4 30 15 50 2 17 43 2 1 14 3 15 79 8 185 4 9 41 15 100 5 1 23 6 3 44 20 62 All reporting mills 49 52 2 185 aSee Figure 10 for regions. SOURCE: Joyce et al.
From page 105...
... TABLE 24 Sulfite Pulp and Spent Liquor Solids Production from North American Sulfite Mills Spent Liquor Number ProductionSolids Pulp Grade of Mills (1,000 tons) (1,000 tons)
From page 106...
... Primary sludges contain the material removed from the bottom of a primary collection pond. Primary sludge contains about 65 percent water and, due to its consistency, it is difficult to remove additional water mechanically.
From page 107...
... Chemical Composition Information on the composition and in vitro rumen digestibility of several pulpmill residues is shown in Table 27 and in Appendix Tables 1 to 4. Fines and screen rejects are very low in protein, and high in acid detergent fiber.
From page 108...
... The mixed hardwood, bleachedkraft chemical pulp fines are essentially pure cellulose. Table 27 shows that the lignin and total carbohydrate contents of the aspen groundwood, aspen sulfite screen rejects, and aspen sulfite parenchyma cell fines are almost identical, whereas the in vitro dry-matter digestibility ranges from 37 to 73 percent.
From page 109...
... (1973) offered Hereford steers diets containing 0 and 50 percent unbleached southern pine kraft pulp fines for a period of 58 days.
From page 110...
... In the second, a diet of 70 percent barley and 30 percent alfalfa was compared with those diets containing approximately 70 percent of the bleached sulfite pulp and three different nitrogen sources. In all cases the pulp-fed lambs had desirable carcass characteristics equivalent to or higher than the controls.
From page 111...
... The use of additional spent sulfite pulp fines in animal diets requires study to determine how to make the material available without causing serious changes in the material and energy balances in the pulpmills and how best to utilize it near its source. Potential The results of these studies involving pulpmill residues showed that the cellulosic fiber fines from two pulpmills, each producing about 31 metric tons (dry basis)
From page 112...
... Groundwood mill Mixed species plus some mixed chemical pulps 50 41 38 24 Southern pine plus some hardwood kraft 24 60 15 19 Semichemical pulpmill Aspen 20 71 2 57 Aspen plus mixed hardwoods 55 29 13 6 Chemical pulpmill De-inked wastepaper, tissue 23 71 22 72 Softwood sulfite, glassine 13 74 14 66 Reprocessed milk carton stock 28 67 25 65 Mixed chemical pulps, tissue 17 76 13 60 Mixed hardwood bleached kraft, printing 17 75 11 59 Aspen sulfite, tissue 19 77 2 50 Aspen and spruce sulfite, tissue 45 46 45 35 Secondary waste treatment sludge 38 5 45 5 aIncludes ash not soluble in H2SO4 SOURCE: Millett et al.
From page 113...
... Wood residues have been investigated for this purpose. Aspen sawdust has been shown effective as a partial forage substitute in a high-grain dairy diet (Salter et al., 19701.
From page 114...
... It is essential, however, that diets containing wood residues be properly balanced for all of the essential nutrients. Wood residues must be considered primarily as energy sources.
From page 115...
... This causes problems in storage because of deterioration. Research is needed to identify low cost means of preserving high moisture wood residues.
From page 116...
... For lactating dairy cows, aspen sawdust could be used as a roughage extender or as a partial roughage substitute in high-grain diets. Some long hay appears to be necessary in the diet to stabilize feed intake.
From page 117...
... 1973. Effect of lignin on the in vitro digestibility of wood pulp.
From page 118...
... 1979. Quantity and composition of pulp and papermill primary sludges.
From page 119...
... 1970. Aspen sawdust as a partial roughage substitute in a high-concentrate dairy ration.
From page 120...
... 1979. Forest Biomass as an Energy Source.


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