Nutritive value of leaves and pruning residues of red and white grapevine (Vitis vinifera L.) varieties

Interest in the green pruning residues of grapevine (GPR), harvested in spring, and in grapevine leaves (GL), harvested in autumn, as a feedstuff, has been increasing due to their nutritive value. The aim of this study has been to investigate the differences between the chemical composition, gross energy (GE) and in vitro apparent digestibility (DMD) of the GPR and GL of five varieties of red grapevine (Cabernet franc, Canaiolo nero, Carignan noir, Lambrusco salamino, and Sangiovese) and of five varieties of white grapevine (Malvasia bianca di Candia, Moscato bianco, Sauvignon blanc, Verdicchio and Vernaccia di S. Gimignano). The dry matter, acid and neutral detergent fibre, GE and DMD were found to differ (P < 0.01) between cultivars for both GPR and GL, while no significant differences were observed between the cultivars, in terms of their mean acid detergent lignin content for GPR and crude protein content for GL, respectively. In conclusion, the results show that both the GL and GPR obtained from red and white grape varieties originating from Italy are suitable dietary sources for ruminant feeding, even though GL has a lower fibrous content than GPR and, consequently, a higher DMD.