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The objective was to evaluate the fermentation profile, in vitro gas production and nutritional quality of pornunça (Manihot spp.) silages containing levels of condensed tannin (CT; 0, 4, 8 and 12% on dry matter (DM) basis), at five opening times (0, 3, 7, 14, 28 and 56 days). A completely randomized design in a 4 × 5 factorial arrangement was adopted, with four replications, totalling 80 experimental silos. The pH and NH3-N analyses were performed at all opening times of the silos. The other analyses were performed only with silages opened at 56 days of storage. There was an interaction effect between CT levels and silo opening times for pH and NH3-N. Tannin levels in pornunça silages after 56 days ensiling increased the pH and DM and reduced crude protein (CP) and neutral detergent fibre (NDF). There was a quadratic effect for NH3-N, acetic acid, butyric acid, gas losses, dry matter recovery (DMR), hemicellulose and acid detergent fibre. Inclusion of 4 and 8% CT in pornunça silage promotes a rapid decline in pH, being within the acceptable limit for adequate fermentation at 3 days of ensiling. Silages with 4% CT establish the pH at 28 days of opening the silos, with reduced NH3-N. Silages with 4% CT present higher concentrations of acetic and butyric acids and greater DMR. Inclusion of CT in pornunça silage after 56 days ensiling increases DM and reduces CP and NDF, directly affecting the in vitro degradability and reducing gas production.

The objective of this study was to determine the greatest concentration of condensed tannin (CT) extracted from Schinopsis brasiliensis in pornunça silages based on intake, digestibility, milk production, ingestive behavior and estimated greenhouse gas (GHG) emissions in dairy goats. Eight multiparous Saanen goats at 30 days of lactation, with 38.0 kg of initial body weight, production of 2.0 ± 0.4 kg of milk/day, mean age of 2–3 years, were distributed in a double Latin square (4x4) with four experimental periods and four diets with different tannin levels at concentrations 0% (control), 2.4, 3.6 and 4.8% tannin of total diet. The CT levels in the silage of pornunça promoted a linear decrease for the intake of dry matter (DM, P < 0.001), organic matter (OM, P < 0.001), ash (P < 0.001), crude protein (CP, P < 0.001), neutral detergent fiber (NDF, P < 0.001), acid detergent fiber (ADF, P < 0.001) and water (P < 0.001). The inclusion of CT also promoted a linear decrease in apparent digestibility coefficients of DM (P < 0.001), OM (P < 0.001) and CP (P < 0.001), milk production (P < 0.001), NDF (P < 0.001), and GHG emission estimation (P < 0.001). The intake and rumination rates of DM and NDF showed a linear decrease (P < 0.001) with level of tannin in the diets. In the experimental conditions, the inclusion of condensed tannin extracted from Schinopsis brasiliensis in pornunça silages, at levels up to 2.4% DM basis, promotes a decrease in intake of DM (DMI) and OM (OMI) and milk production as decreases GHG emissions in Saanen goats.

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