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Title: Effects of forage-to-concentrate ratio and dietary fiber manipulation on gas emissions and olfactometry from manure of Holstein heifers

Author
item LASCANO, GUSTAVO - Clemson University
item HEINHRICHS, JUD - Pennsylvania State University
item GARY, RICHARD - California Polytechnic State University
item TROPPER, PATRICK - Pennsylvania State University
item BRANDT, ROBIN - Pennsylvania State University
item Adviento-Borbe, Arlene
item FABIAN, EILEEN - Pennsylvania State University

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2014
Publication Date: 1/15/2015
Publication URL: http://handle.nal.usda.gov/10113/5395538
Citation: Lascano, G., Heinhrichs, J., Gary, R., Tropper, P., Brandt, R., Adviento-Borbe, A.A., Fabian, E. 2015. Effects of forage-to-concentrate ratio and dietary fiber manipulation on gas emissions and olfactometry from manure of Holstein heifers. Journal of Dairy Science. 98:1928–1937.
DOI: https://doi.org/10.3168/jds.2014-8633

Interpretive Summary: The U.S. Dairy industry is estimated at $140 billion in economic output. National policies and regulations such as The Clean Air Act by US Environmental Protection Agency which established national air quality standards are affecting the production and operation of dairy farms. Dairy operations are associated with emission of odor, particulate matter and greenhouse gases. Feed manipulations such as low fiber meal will decrease organic matter and nutrients in feces and potentially reduce greenhouse gas and ammonia emissions from cow manure. Ammonia, CH4, N2O, CO2 and odor emissions were measured from manure excreted by cows that fed with different fiber and concentrate feed ratios. Fiber and concentrate ratio high in neutral detergent fiber (NDF) formulation shifted the proportion of excreted urine and feces and led to differences in emissions of odor, ammonia and CH4 from cow manure. This information provides commercial dairy farm operators on the appropriate feed diet ratio to implement in order to manage emissions of CH4 and ammonia gas from dairy facilities.

Technical Abstract: The objective of this experiment was to determine the effects of differing ratios of forage to concentrate (F:C) and fiber levels on odor and gas emissions from manure. Eight Holstein dairy heifers (362.45 ± 4.53 d of age and 335.6 ± 7.41 kg of body weight) were randomly assigned to a split-plot, 4 × 4 Latin square design (21-d periods) with F:C as the whole plot (20 or 80% forage) and fiber level as sub-plot (0, 20, 40, or 60% inclusion of corn stover). Gas concentration was determined using an infrared photoacoustic analyzer over a 24-h period using a steady-state flux chamber setup. Odorous air samples were collected from chamber headspace and evaluated by 6 human assessors using a forcedchoice dynamic olfactometry technique. Emissions of CO2 were greater for the low than high concentrate diets, and no differences were observed for NH3 and CH4 emissions between F:C. Although F:C had no effect on NH3 emissions, as dietary fiber increased, a linear interaction with opposite effects was found for high and low concentrate diets. Nitrous oxide emissions were below minimum detectable levels. Neither F:C nor neutral detergent fiber level affected odor intensity. Odor emissions were successfully assessed, and manipulation of dietary fiber has the potential to influence CH4 and NH3 emissions.