Hedges and woody strips browsing by cattle on pasture in Wallonia, Belgium

Agri-environmental measures promote woody hedges along meadows in Wallonia, raising the interest in tree and shrub as forage in intensive mixed dairy temperate production systems. This study aimed at (1) determining the influence of an access to hedges on the grazing behavior of young cattle and (2) assessing the fermentation characteristics of woody species promoted in Wallonia. Twelve heifers, divided in two groups, were set to graze a ryegrass and white clover-based pasture in May 2012. The first group had access to a hedge composed of 12 temperate tree and shrub species, and the second group grazed the pasture only. The grazing and browsing behavior of the animals was recorded for 4 weeks along with pasture biomass availability, using the hand-plucking method. Samples of the 12 tree species were fermented using rumen fluid in an automated gas pressure monitoring system and gas production kinetics compared to ryegrass and white clover. Results suggest that the feeding behavior was influenced by the hedge. Grazing time of the control group was higher than heifers that could browse woody foliage (P<0.05). Browsing was especially noticeable when grass availability on pasture was lowest. In vitro ruminal fermentation kinetics differed among species (P<0.01) with Populus nigra and Fraxinus excelsior showing a potential of fermentation similar to herbaceous forages. It can be concluded that due to the browsing by cattle some woody species could be interesting as complementary feeding. Besides their attributes regarding the agricultural landscape, their feeding qualities should be considered when planting the hedges.