Seasonal variation of nutritional characteristics of some Mediterranean shrub species

摘要

The aim of this study was to determine the chemical composition and in vitro dry matter digestibility of eight browse species {Arbutus unedo, Calicotome villosa, Cistus salvofolius, Erica arborea, Myrtus communis, Phillyrea angustifolia, Pistacia lentiscus and Quercus suber) harvested in spring and summer from uplands in the province of Nefza (Norwest Tunisia). Species varied widely in their crude protein content (CP, 38-221 gkg~(-1) dry matter (DM)), cell wall content (NDF, 325-630 gkg~(-1) DM), condensed tannins (1-570 g kg~(-1) DM) and in vitro dry matter digestibility (IDM) (430-681 gkg~(-1) DM). CP content and digestibility coefficients tended to decrease from spring to summer (P<0.001), whereas NDF and tannin contents followed the opposite trend. NDF fraction may have a negative influence on browse digestibility. Based on these results, it is concluded that some of these species may represent a high quality feeding resource for grazing ruminants in the rangelands, particularly when the herbage availability is reduced.