Potential of fodder trees in high-output dairy systems

The reform of the EU’s Common Agricultural Policy (CAP) has created renewed interest in the implementation of agroforestry and silvopastoral systems. The multifunctional use of trees for energy and wood production, nutrient cycling, carbon storage, biodiversity, landscape quality and – last but not least – fodder makes trees a potential third crop next to grass and maize on farmland including high-output dairy farms. To decide which trees to use for planting, it is important to have insight into the feeding value of the different species. Therefore we created a database on the feeding values, using data from the literature. The database includes records of tree leaves, twigs, and twigs with leaves of 40 different temperate tree species (620 records in total) (www.voederbomen.nl/nutritionalvalues). Using this database, we compared the nutritive value of the leaves of a number of temperate fodder trees. The nutritive values for grass (Lolium perenne L.) are shown for comparison. These data show that, compared to grass, the in vitro organic matter digestibility of tree leaves is relatively low. However, for some species the concentrations of crude protein, and of macro- and micronutrients, are relatively high, which shows the potential value of tree leaves as an additional feed source on dairy farms.