Potential mechanisms to increase shrub intake and performance of small ruminants in mediterranean shrubby ecosystems

Shrubby vegetation types called “maquis” and “garrigue” are widespread throughout the Mediterranean Basin, including the Adriatic littoral of Croatia. In Croatia and elsewhere, these shrublands represent traditional grazing areas and are a significant source of forage for small ruminants, particularly during the dry summer. Utilization of these Mediterranean shrublands is often limited by secondary compounds that adversely affect forage intake and animal health. Likewise, shrubs containing substantial quantities of secondary compounds dominate arid and semiarid rangelands globally. These secondary compounds reduce livestock productivity, cause significant toxicity and abortion problems, and reduce efficiency of use of rangeland shrubs worldwide. Feed additives (e.g., activated charcoal, polyethylene glycol, and calcium hydroxide) may be useful for enhancing shrub intake through decreased absorption and/or increased elimination of secondary compounds. The biological diversity of Mediterranean maquis vegetation may also positively influence shrub consumption by small ruminants. Consumption of combinations of shrubs containing varied classes of secondary compounds (e.g., tannins and saponins) may lead to complementary chemical interactions within the intestinal tract and/or post-absorption that reduces their toxic effects and/or increase efficiency of detoxification. Although goats consumed more total shrubs than sheep across experiments, both species responded similarly to supplemental charcoal, PEG, and calcium hydroxide. © 2007 Elsevier B.V. All rights reserved.