Nutritive evaluation of some native range plants and their nutritional and anti-nutritional components

Nutritive values of some native drought-tolerant range perennial shrubs (Artemisia herba-alba, Noaea mucronata, Lavandula officialis, Astragalus spinosus, Capparis spinosa) grown naturally on the south-eastern semi-desert of Syria were evaluated by determination of the in vitro digestible organic matter (IVDOM), metabolizable energy (ME) and net energy lactation (NEL) and the presence of nutritional and anti-nutritional components. The highest concentrations of crude protein and buffer soluble nitrogen (BS-N) were in C. spinosa (229 and 19 g/kg DM, respectively), whereas the lowest concentrations were in other experimental plant species (97-104 and 6-8 g/kg DM, respectively). A. herba-alba had high concentrations of total phenols (TP) and hydrolysable tannins (HT; 45 and 23 g/kg DM, respectively). The range plants had low concentrations of condensed tannins (0.4-1.1 g/kg DM). The IVDOM, ME and NEL values of the evaluated species amounted to 481-702 g/kg DM, 6.25-9.08 MJ/kg DM and 3.03-4.54 MJ/kg DM, respectively. The descending order (P <0.05) of the plant species on the basis of their content of IVDOM, ME and NEL was C. spinosa>A. spinosus>L. officialis>A. herba-alba>N. mucronata. The addition of polyethylene glycol (PEG, 6000) to the plant samples incubated with rumen fluid at a ratio of (2:1 PEG:substrate) did not increase the values of IVDOM, ME and NEL. IVDOM, ME and NEL were negatively correlated with crude fibre and cell wall constituents but positively correlated with crude protein and BS-N. The TP and HT concentrations were negatively correlated with BS-N, but positively correlated with lignin. On the basis of protein and energy, the evaluated species were nutritionally well suited as dietary supplements for ruminants in arid regions.