Bark in feed – for improved feed utilization and animal health
The inclusion of condensed tannins (CT) in the diet of ruminants may enhance protein utilization, reduce enteric methane emission and problems with gastrointestinal parasites. Tanniferous forages are not well adapted to soil and climatic condition in Middle-Norway, but the region has a strong forest industry and bark from trees growing and harvested in the region may have high content of CT. Recent international research has shown that inclusion of bark in the diet of ruminants may have the abovementioned beneficial effect. The results cannot, however, be directly related to the tree species and conditions available in Middle Norway. Using a combined approach (literature review and experimental work) we will assess if and how CT in bark of Scots pine (Pinus sylvestris), Norway spruce (Picea abis) and birch (Betula pubescens) can be utilized as feed supplement. We will characterize the concentration, variation and type of CT in bark sampled from commercial saw-mills and in fresh bark at logging. The acquired information will help us to assess which source of CT are most suitable for use as feed supplement, and whether isolation and purification of bark CT is required for optimum use. If the results show that concentration of relevant substances is a prerequisite for successful utilization, techniques, equipment, efficacy and costs of industrial concentration-processes will be assessed