191 - Evaluation of Diverse Cool-season Grass Mixtures with Red Clover on Ruminal Fermentation in Continuous Culture

Tuesday, June 28, 2022

3:35 PM – 3:50 PM CT

Location: Oklahoma City Convention Center, 207 A/B

Presenting Author(s)

MS

Miriam A. Snider, MS

Graduate Research Assistant
University of Vermont
Burlington, Vermont

Author(s)

BM

Bharath K. Mulakala

University of Vermont
Burlington, VT
AD

Ashley W. Driemel

University of Vermont
Burlington, VT
SZ

Sara E. Ziegler, n/a

Research Specialist
UVM Extension Northwest Crops and Soils Program
St. Albans, VT
HD

Heather M. Darby

Professor & Agronomic and Soils Specialist
UVM Extension Northwest Crops and Soils Program
St. Albans, VT
Kathy J. Soder, n/a

Animal Scientist
USDA-ARS
University Park, PA
AB

Andre F. Brito, n/a

Associate Professor of Dairy Cattle Nutrition and Management
University of New Hampshire
Durham, NH
SG

Sabrina L. Greenwood, n/a

Associate Professor
University of Vermont
Burlington, VT

Abstract: Dual-flow continuous culture fermenters were used to evaluate the impacts of forage mixtures on ruminal fermentation. Diets (DM basis) contained 40% red clover combined with 1) 60% orchardgrass (OG); 2) 30% orchardgrass + 30% meadow fescue (MF); 3) 20% orchardgrass + 20% meadow fescue + 20% Kentucky bluegrass (KYBG); or 4) 15% orchardgrass + 15% meadow fescue + 15% Kentucky bluegrass + 15% perennial ryegrass (PRG). Treatments were randomly assigned to fermenters in a 4 x 4 Latin square design. Each 10-d period included a 7-d adaptation and 3-d sampling period. Diets (110 g DM/d) were added across 4 feedings/d (33% each, 0700 h and 1600 h; 17% each, 0820h and 1720 h). Fermenter pH was recorded continuously for 10-d. Methane was measured on d 7-10 at 0630 and 1530 h. Effluent samples were collected on d 8-10. Results were analyzed using PROC GLIMMIX of SAS with significance at P ≤ 0.05. Apparent digestibility of DM, OM, NDF, and ADF was greatest (P ≤ 0.05) for fermenters receiving KYBG, followed by PRG. Apparent DM and OM digestibility for OG and MF were less than KYBG by 18.0% and 19.6%, respectively. Fermenters receiving KYBG spent the greatest amount of time under pH 5.8 (avg. 15.5 h/d; P = 0.0004). Acetate:propionate and acetate + butyrate:propionate ratios were greater for fermenters receiving KYBG (4.09 and 4.71) and PRG (4.03 and 4.65; P < 0.0001). Water soluble carbohydrate concentration of effluent was least for KYBG (0.80 mg/ mL; P ≤ 0.05). Methane output for KYBG (116.8 mg/dL; P < 0.0001) was greater than that of OG (13.7 mg/dL), MF (31.7 mg/dL), and PRG (11.9 mg/dL) which did not differ from one another. These results suggest that diets containing KYBG and PRG were more digestible with PRG having the added benefit of decreased methane output.