Condensed tannins extracted from Quebracho affect the fermentation profile, nutritional quality and in vitro gas production of pornunça (Manihot spp.) silages

Abstract

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.