 The new technologies used to analyze molecular and chemical structures have shown that a division into condensed and hydrolyzable tannins is too simplistic.Recent studies have demonstrated that products containing chestnut tannins included at low dosages (0.15–0.2%) in the diet of chickens may be beneficial.Some studies suggest that chestnut tannins have positive effects on silage quality in the round bale silages, in particular reducing NPNs (non-protein nitrogen) in the lowest wilting level.