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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Publications at this Location » Publication #334176
Title: Evaluation of a novel continuous culture fermentor system for determination of ruminal fermentation and methane production

Author
item Dillard, Sandra
item ROCA-FERNANDEZ, ANA - Universidad De Chile
item TILLMANN, RYAN - Pennsylvania State University
item RUBANO, MELISSA - University Of Maryland Eastern Shore (UMES)
item Soder, Kathy

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2019
Publication Date: 6/9/2019
Citation: Dillard, S.L., Roca-Fernandez, A., Tillmann, R., Rubano, M., Soder, K.J. 2019. Evaluation of a novel continuous culture fermentor system for determination of ruminal fermentation and methane production. Journal of Dairy Science. 103:1313-1324. https://doi.org/10.1111/jpn.13155.
DOI: https://doi.org/10.1111/jpn.13155

Interpretive Summary: Continuous culture fermentor systems are important laboratory tools that allow researchers to screen a large number of ruminant diets at a small scale to determine digestive characteristics at much lower cost than animal studies. Results of these studies can then be refined and evaluated in animal-level experiments. This study by ARS scientists at the Pasture Systems and Watershed Management Research Unit in University Park, PA evaluated a new fermentor system to more accurately assess nutrient digestion and greenhouse gas emissions of ruminant diets. Use of this new system will allow researchers to more precisely describe ruminal fermentation and methane production of feedstuffs than previous systems to further reduce environmental impact while improving animal productivity and farm profitability of dairy and livestock systems.

Technical Abstract: A novel, 4-unit, continuous culture fermentor system was developed to assess nutrient digestibility, volatile fatty acid (VFA) production, bacterial protein synthesis, and CH4 production of ruminant diets in vitro. The diet consisted of 50% orchardgrass (Dactylis glomerata L.) and 50% alfalfa (Medicago sativa L.) fed during 4, 10-d periods (7-d adaptation and 3-d collection). Fermentors were fed 82 g dry matter (DM)/d in equal portions 4 times daily (0730, 1030, 1400, and 1900 h). Measurements for pH and temperature were taken every 2 min and a photoacoustic gas analyzer was used to measure CH4 concentration of the vessel headspace every 10 min. Samples for DM and protozoa were taken daily at 1000 h from the vessel and daily effluent samples were collected for determination of VFA, DM, and NH3-N concentrations. Herbage samples were also analyzed for DM, organic matter (OM), crude protein, and fiber fractions and effluent was collected and composited across the collection days for determination of DM, OM, NDF, and ADF apparent digestibility and true digestibility of DM and OM. There was no effect of adaptation vs. collection days on vessel and effluent DM, temperature, or mean, maximum, and minimum pH. Initial protozoal counts decreased after inoculation, but recovered by the collection period. Total VFA concentration did not differ among periods or between days of the collection period. There was no difference among days or periods in total daily CH4 production and CH4 production per OM, NDF, digestible OM, or digestible NDF fed. Data collected throughout 4 experimental periods demonstrated that the system was able to reach a steady-state in fermentation well within the 7-d adaptation period and even typically variable data (i.e., CH4 production) was stable within and across periods. While further research is needed to determine the relationship between this system and in vivo data, this continuous culture fermentor system provides more robust data than previously developed systems.