The evaluation of the nutritional potential of five Mediterranean woody plants rich in phytocompounds

Abstract

The foliage of woody plants, Artemisia herba alba (ART), Eucalyptus globulus (EUC), Pistacia lentiscus (PIS), Rosmarinus officinalis (ROS) and Thymus capitatus (THY), growing in central Tunisia was analysed for contents of nutrients and phytocompounds, including essential oils (EOs) and tannins. PIS and THY were highest in neutral detergent fibre and condensed tannins, respectively. EUC had the highest levels of total phenols, total tannins and oxalates. The concentration of EOs was highest in ROS and THY (26.59 ml . kg(-1) dry matter (DM) vs 14.14 ml . kg(-1) of DM, respectively). The EOs profiles differed among all the plant species. ROS and EUC EOs were composed mainly of 1,8-cineole (27.86% and 50.19%, respectively) while ART's EOs were dominated by camphor (16.28%) and chrysanthenone (14.78%). Carvacrol (44.24%) was the chemotype of THY EOs. The major compound of PIS EOs was alpha-pinene (12.82%). Biological assay showed that tannins affect the nutritive value of these plants. With the exception of THY, the association of polyethylene glycol to substrates incubated in calibrated syringes resulted in a major increase of gas production (+21% to +136%). Differences in the profiles of EOs extracted from the five woody species suggest that these EOs could differ in their impact on digestion and performance of ruminants.