|Roca-fernandez, Ana - Universidad De Chile|
Submitted to: Third Grazing Livestock Nutrition Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/2016
Publication Date: 7/22/2016
Citation: Roca-Fernandez, A., Dillard, S.L., Rubano, M.D., Dell, C.J., Soder, K.J. 2016. Effect of condensed tannins on forage nutritive value and greenhouse gas output of an orchardgrass diet. Proceedings of the 5th Grazing Lands Nutrition Conference, July 16-19, 2016, Park City, Utah. P.1.
Interpretive Summary: No Interpretive Summary is need for this Abstract Only.
Technical Abstract: Greenhouse gas (GHG) emissions from livestock account for 43%, 29%, and 27% of CH4, N2O and CO2, respectively, of global GHG emissions from livestock. Legumes containing condensed tannins (CT) have been shown to decrease enteric CH4 in ruminants; however, research is lacking on how increased CT levels affect forage nutritive value and other GHG output. A 4-unit, dual-flow continuous culture fermentor system was used to assess GHG output (CH4, CO2 and N2O) of CT legumes in an orchardgrass (Dactylis glomerata) diet. Treatments included: alfalfa (ALF, Medicago sativa) used as control, birdsfoot trefoil (BFT, Lotus corniculatus) as a low CT legume (7% CT, DM basis), crown vetch (CV, Coronilla varia) as an intermediate CT legume (12% CT, DM basis), and sericea lespedeza (SL, Lespedeza cuneata) as a high CT legume (31% CT, DM basis). Treatments were randomly assigned to fermentors in a randomized block design with 3 replicates. Feedings occurred 4 times daily throughout 3, 10-d periods using 7 d for adaptation and 3 d for collection. Treatments consisted of 50% orchardgrass and 50% legume. Forage samples were analyzed for DM, OM, protein fractions, fiber, lignin and NEL. Greenhouse gas output was measured continuously during the collection period using a photoacoustic field gas monitor (INNOVA 1412; Air Tech Instruments, Denmark). Gas samples were analyzed using GLIMMIX procedure of SAS (SAS Inc., Cary, NC) with treatment and period as fixed effects and fermentor as random effect. Pearson correlation coefficients between gas output and forage characteristics were determined using PROC CORR, and stepwise linear regression analysis was conducted using PROC REG to detect predictive statistical associations between gas output and forage characteristics. Sericea lespedeza reduced (P < 0.011) CH4 output by 9% compared to ALF, BFT and CV. The CO2 output of CV was 3, 6, and 8% less (P < 0.001) compared to SL, BFT and ALF, respectively. There were no differences (P > 0.960) in N2O output among treatments. There was a positive correlation between CH4 output and degradable protein (r = 0.840, P < 0.001) and CP (r = 0.652, P = 0.022). There was a negative correlation between CH4 output and CT (r = -0.846, P < 0.001) and OM (r = -0.643, P = 0.024). Regression analysis revealed that CT explained 72% of the variation in CH4 output across all CT legumes. To conclude, increased CT in SL reduced CH4 output and was affected by protein content. Keywords: condensed tannins, continuous culture, greenhouse gas