Tannin content of selected fodder trees and shrubs and their effect on in vitro digestibility
1994
Koukoura, Z.S. | Nastis, A.S. (University of Thessaloniki (Greece). Laboratory of Range Science)
Ten fodder trees and shrub species growing in the Mediterranean zone are examined in this paper. Arbutus unedo, Arbutus andrachne, Arbutus andrachnoides, a hybrid (Arbutus unedo X Arbutus andrachne), Amorpha fruticosa, Colutea arborescens, Gleditshia triacanthos, Morus alba, Morus alba cv. Kokuso 21, Robinia pseudoacacia, Phillyrea media. Browse samples were harvested in late May (spring stage) and in late July (summer stage). Samples were analysed for total phenolics content (Folin-Denis assay), condensed tannins (vanillin-HC1 assay) and their astrigency effect (haemoglobin precipitation assay) as well as for the in vitro dry matter digestibility (IVDMD). Total tannin concentration was more than twice as much from that of alfalfa during the spring stage for all fodder and shrub species tested. The general trend was for decreased total and condensed tannin content with maturation. The astrigency effect though had an increased trend with maturation. Negative correlations were found only between the digestibility and astrigency assays in both phenological stages, higher in the Summer than in the Spring.
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