Nutritional and Phytochemical Profiling of Bourdim Forest Shrubs Selected by Small Ruminant Foraging Preferences (Northeastern Algeria)

Managing Mediterranean forest ecosystems requires a deep understanding of the nutritional value of understory vegetation utilized by grazing livestock. This study aimed to evaluate the primary and secondary chemical compositions of two key Mediterranean shrub species in the Bourdim forest (Northeastern Algeria) to assess their suitability and safety as extensive forage resources. A preliminary herd-tracking survey was conducted within the forest to monitor the dietary preferences and selective behavior of grazing animals. Based on these field observations, two highly consumed species, Viburnum tinus and Cistus monspeliensis, were selected for detailed laboratory analysis during the spring season. Leaf samples were analyzed for dry matter (DM), mineral matter (MM), Crude protein (CP), fiber fractions (NDF, ADF, ADL), saponins, total phenols, total tannins, and condensed tannins. Saponin hemolytic activity was also quantified. The results revealed contrasting nutritional profiles between the two species. C. monspeliensis demonstrated a high crude protein content (17.7% DM) and superior mineral content (7.40% DM). Conversely, V. tinus exhibited critically low protein levels (1.12% DM), well below the minimum threshold required for optimal rumen microbial activity. Fiber fractions (NDF, ADF, ADL) were relatively similar between species, suggesting comparable potential digestibilities. Regarding secondary metabolites, C. monspeliensis displayed significantly higher total phenols and total tannins (31.5 and 26.48 g tannic acid eq./kg DM, respectively). While V. tinus contained slightly higher saponin levels, C. monspeliensis exhibited a severe hemolytic activity of 55%, compared to only 5% for V. tinus. Although selected by grazing herds, these forest shrubs present specific metabolic constraints. C. monspeliensis is an excellent source of protein but requires moderate ingestion due to high hemolytic activity and tannin levels that may restrict nutrient degradability. V. tinus provides moisture and fiber but requires protein supplementation in extensive production systems to prevent rumen dysfunction.