The nutritive value of different Mediterranean browse species used as animal feeds under oak silvopastoral systems in Northern Portugal

Oak woodlands (OW) have historically been important in the Mediterranean region since they provide an important amount of goods and services, such as fodder and shelter for extensive livestock production systems. However, OW lost relevance as a fodder supplier due to the specialization and intensification of livestock production. Nowadays, with the challenges emerging from climate change and other environmental concerns, OW are regaining interest as silvopastoral systems. The aim of this study was to evaluate the seasonal variation of the chemical composition and the in vitro organic matter digestibility (IVOMD) of key browse species in grazed OW in the north of Portugal. Additionally, the feeding value was compared with the requirements of goats’ maintenance and late pregnancy. The browse species evaluated were Quercus suber, Q. rotundifolia, Q. faginea, Juniperus oxycedrus, Cytisus scoparius, C. multiflorus, Genista falcata, Cistus ladanifer, and Lavandula stoechas. The data were analysed by a two way analysis of variance focusing on species and season and their interaction. The results obtained varied significantly among the species studied regarding the crude protein content (CP) (41.6–195.9 g kg⁻¹ dry matter (DM)), fibres (neutral detergent fibre (NDF): 316.7–632.5 g kg⁻¹ DM; acid detergent fibre (ADF): 246.0–468.0 g kg⁻¹DM; acid detergent lignin (ADL): 90–210.5 g kg⁻¹ DM), IVOMD (33.02–71.34%), and metabolizable energy (ME) (5.78–11.42 MJ kg⁻¹ DM). Both C. ladanifer and Q. rotundifolia have inadequate ME and CP levels to meet the nutritional needs of goats with 45 kg of live weight. Only leguminous shrubs cover CP needs in late pregnancy.