11 Inclusion of Quebracho Tannin as a Silage Additive in Tall Fescue Silage: Effects on Fermentation

Abstract

Abstract Tall fescue (Schedonurus arundinaceus) is commonly grazed in the mid-south, but also has potential use for spring silage. During ensiling, protein can be converted to ammonia, but condensed tannins such as those in Quebracho (Schinopsis quebracho-colorado) can reduce this conversion. However, acid production may also be reduced. Quebracho tannin was added to chopped tall fescue and ensiled at different moisture concentrations to determine those effects on ammonia and silage fermentation products. Tall fescue was harvested with a Carter harvester at 1000 h, spread on concrete, mixed thoroughly, and dried for 1 and 2 h to achieve 67 and 44% moisture (high moisture (HM) and low moisture (LM), respectively). Quebracho tannin was either not applied, or was mixed with distilled water 48 h prior to packaging and applied at 1 and 2% of the total silage dry matter (DM) to both moisture treatments. Laboratory silos were pressed to achieve a packing density of 192 kg/m3 and stored at room temperature (23.7 ℃) for 60 d, after which sub-samples were removed and analyzed for fermentation parameters. Post-ensiling crude protein (CP) was greater (P < 0.05) from LM vs. HM, but did not differ among tannin treatments (P = 0.11). Ammonia concentrations (%CP equivalent) were greatest in 0% tannin (P < 0.05). A moisture by tannin interaction affected acetic acid, with greater concentrations in HM silages with 0 and 2% tannin compared to LM with 2% tannin. Lactic acid (%) was greater (P < 0.05) in 0 compared to 2% tannin, but 1% did not differ from either 0 or 2% tannin. Butyrate was greater (P < 0.05) in HM, and in silos with 2% tannin, but not 1% tannin. Overall, total acids (%) were greatest (P < 0.05) in HM but did not differ (P = 0.54) among tannin treatments. Therefore, ensiling tall fescue with tannins reduced proteolysis regardless of moisture concentration, and did not reduce fermentation up to 2% tannin inclusion.