Utilization of low quality resources by small ruminants in Mediterranean agro-pastoral systems: the case of browse and aftermath cereal stubble

Browse and cereal stubble represent the two most important resources for gr azing small ruminants in dry Mediterranean areas. The purpose of the presen t review is to provide updated information regarding their nutritional valu e. In a mixed Mediterranean environment? browse represents at least 40% of goat's diet. Most browse species in the Mediterranean are rich in tannifero us phenolic substances. Polyethylene glycol (PEG) can bind tannins irrevers ibly over a wide range of pH and is efficient in alleviating the negative e ffects of tannins. Supplementing with PEG improves intake and digestibility in grazing goats and sheep and has the potential to be economically profit able. The chemical composition of wheat stubble is affected by the cultivar of wheat and climate, but not tillage management. The quality of stubble f rom early maturing is lower than from late maturing cultivars. Stubble cont ains more protein in years of lower rainfall. If grains escaped from the ha rvest combine (2% of grain yield) are included, digestibility of OM from di fferent components ranges between +/-80% (grain) to +/-40% (stem). Also, th e energy requirement of sheep grazing on stubble may be 70% higher than in shaded feedlot. Therefore, the body condition changes of sheep grazing on s tubble exhibit a cyclic pattern consequent with temporal changes in nutriti ve quality. Because stubble grazing is concurrent with the onset of oestrou s season, supplementation with grains from legume species-rich in degradabl e protein-is needed to prevent impairment of body condition. Supplementing browsing goats with PEG, and sheep grazing cereal stubble with moderate amo unts of legume grain, may enable the use of these traditional resources in the frame of sustainable production systems.