Supplementation of Oilseeds to an Herbage Diet High in Condensed Tannins Affects Methane Production with Minimal Impact on Ruminal Fermentation in Continuous Culture

Condensed tannins (CT) have been observed to reduce enteric CH4 production when added ruminant diets. However, high concentrations of CT in forages such as sericea lespedeza (SL; Lespedeza cuneata (Dum. Cours.) G. Don) may depress nutrient digestibility. Oilseed crops, lipid concentration, also via toxicity methanogenic bacteria with less depression it is unclear whether combining these two feeds would result even greater decreases without impairing ruminal fermentation. This study used an vitro continuous culture fermentor system determine if supplementation ground oilseeds further while improving digestibility high-CT forages. The experimental design was a 4 × Latin square, four diets containing (dry matter basis) 45% orchardgrass (OCH; Dactylis glomerata L.), Don), and 10% oilseed supplements, using canola (CAN; Brassica napus soybean (SOY; Glycine max sunflower (SUN; Helianthus annuus or mix all three species (MIX; equal proportions). Fermentors were fed 82 g dry matter/d feedings over 10 d periods. Methane recorded every min, effluent samples analyzed for pH, volatile fatty acids, matter, organic crude protein, neutral detergent fiber, acid fiber apparent true digestibilities. CAN, SUN, MIX had fat (7–8 g/kg) than the SOY diet (5.7 g/kg), which contributed reduction those (13–27 mg/d) compared (84 mg/d). Apparent digestibilities not affected by addition oilseeds. While N intake increased concomitant protein increases diets, there no additional effects on flows. supplementing any (canola, soybean, sunflower, mixture oilseeds) reduced total emission depressing digestibility, mixes most effective. Further research needed vivo evaluate results translate feed efficiency animal production.