Abstract
Eight digestibility trials were performed with rams to evaluate the nutritive values of energy willow leaves (Salix Aqualica), whole short rotation trees (S. Aquatica, S. dasyclados), forest biomass, consisting of branches, foliage and browses, entire hardwood, hydrolysed birch tree pulp and dissolving pulp. The chemical composition of the materials varied according to the leaf-to-wood ratio and the degree of hydrolysis of the pulp. The leaves had high protein contents and low crude fibre contents but remarkably high contents of acid detergent fibre (ADF). The materials containing wood had a high crude fibre content, 41—54 %, as had also both pulps, 44—75 %, but the ADF content was on average 17.4 %-units higher than the content of crude fibre. The lignin content was high in the wood-containing materials (29—34 %) and also high in one of the leaf pulps. The digestibilities of the leaf pulps varied considerably, from 42 to 61 % for DM. The forest biomass had organic matter OM digestibility varying from 20 to 39 %. The digestibility was affected by the ratio of foliage to wood in the material. Hydrolysed wood pulp had poor digestibility, 38 % for OM, but the digestibility of dissolving pulp was comparable to that of good quality roughage, 75 %. The leaf pulps and dissolving pulp had FU values of 0.48—0.69/kg DM. Forest biomass and hydrolysed birch pulp had low values, 0.22—0.34 FU/kg DM. Various energy evaluation systems were compared in the feed value calculations. The fibre correction system gave very low values. Tree foliage and cellulosic wastes with a low lignin content can be utilized as ruminant feed but the possibilities of disposing in this way of cellulosic wastes with high lignocellulosic contents are very limited.
Highlights
Considerable research has recently been devoted to the use of alternative, non-conventional feed sources for animal production
Tree foliage and the unlignified sprout biomass of some short rotation energy woods have proved to have considerable nutritional value (Baertsche 1980) and ensiled green biomass is being investigated as a possible forage crop for cattle feeding (Hooper and Winch 1979)
The willow leaf pulp had a high value for true protein, on average 18.2 %, while the wood pulp materials had a very low value
Summary
Considerable research has recently been devoted to the use of alternative, non-conventional feed sources for animal production. Wastes from the forest industry and the processing of short-rotation or noncommercial trees, and tree residues have received considerable attention as potential feed sources for ruminants (Baker et al 1975, Kommeri 1981, Pohjonen and Näsi 1983). Index words: Forestry by-products, forest biomass, wood residues, tree leaves, ruminant nutrition digestibility of some tree leaves has been found to be moderate and their protein content high (Nasi and Pohjonen 1981, Ciszuk and Murphy 1982). The high cost of pollution control has stimulated active research to evaluate the utilization of waste fibre from the pulping industry as energy feed for ruminants. The object of the present study was to estimate the feed value of some products from short rotation energy willow stands, forest biomass material and wood-processing residues in the diets of ruminants
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