Effect of summer grazing on forage quality of woody and herbaceous species in a silvopastoral system in northern Greece

The forage quality of black locust (Robinia pseudoacacia L.), honey locust (Gleditsia triacanthos L.), bastard indigo (Amorpha fruticosa L.) and white mulberry (Morus alba L.), as well as of the associated herbaceous vegetation, was studied in a silvopastoral system. The study was conducted in a semi-arid grassland with poor sandy soil in northern Greece. Short-duration grazing (28 sheep/ha for 7 days) was repeated twice during the summer period (early July and late August) of 1992, 1993 and 1994. Crude protein content of foliage was maintained at relatively higher levels when plants were grazed compared to control, while neutral and acid detergent fibre content decreased significantly. Crude protein content of black locust and bastard indigo foliage was significantly higher compared to that of honey locust and white mulberry. However, white mulberry presented the highest in vitro digestibility among the four species tested. There was a tendency towards increased in vitro digestibility of the grazed plants' foliage, compared to that of the control (56% and 53.1%, respectively). In addition, short-duration summer grazing resulted in a small increase in the nutritive value and the in vitro digestibility of the associated herbaceous vegetation.