title: Short communication: Comparison of the GreenFeed system with the sulfur hexafluoride tracer technique for measuring enteric methane emissions from dairy cows.
abstract: The objective of this study was to compare 2 commonly used techniques for measuring methane emissions from ruminant animals: the GreenFeed (GF) system and the sulfur hexafluoride (SF6) technique. The study was part of a larger experiment in which a methane inhibitor, 3-nitrooxypropanol, fed at 4 application rates (0, 40, 60, and 80 mg/kg of feed dry matter) decreased enteric methane emission by an average of 30% (measured by both GF and SF6) in a 12-wk experiment with 48 lactating Holstein cows fed a total mixed ration. The larger experiment used a randomized block design and was conducted in 2 phases (February to May, phase 1, and June to August, phase 2), with 2 sets of 24 cows in each phase. Using both GF and SF6 techniques, methane emission data were collected simultaneously during experimental wk 2, 6, and 12 (phase 1) and 2, 9, and 12 (phase 2), which corresponded to a total of 6 sampling periods. During each sampling period, 8 spot samples of gas emissions (staggered over a 3-d period) were collected from each cow using GF, as well as 3×24-h collections using the SF6 technique. Methane emission data were averaged per cow for the statistical analysis. The mean methane emission was 373 (standard deviation=96.3) and 405 (standard deviation=156) g/cow per day for GF and SF6, respectively. Coefficients of variation for the 2 methods were 25.8 and 38.6%, respectively; correlation and concordance between the 2 methods were 0.40 and 0.34, respectively. The difference in methane emission between the 2 methods (SF6 - GF) within treatment was from 46 to 144 and 24 to 27 g/d for phases 1 and 2, respectively. In the conditions of this experiment, the SF6 technique produced larger variability in methane emissions than the GF method. The overall difference between the 2 methods was on average about 8%, but was not consistent over time, likely influenced by barn ventilation and background methane and SF6 concentrations.
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park 16802. Electronic address: anh13@psu.edu.
authors.forename: A N
authors.initials: AN
authors.lastname: Hristov
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park 16802.
authors.forename: J
authors.initials: J
authors.lastname: Oh
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park 16802.
authors.forename: F
authors.initials: F
authors.lastname: Giallongo
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park 16802.
authors.forename: T
authors.initials: T
authors.lastname: Frederick
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park 16802.
authors.forename: M T
authors.initials: MT
authors.lastname: Harper
authors.affiliation: Department of Animal Science, The Pennsylvania State University, University Park 16802.
authors.forename: H
authors.initials: H
authors.lastname: Weeks
authors.affiliation: Departamento de Zootecnia, Universidade Estadual de Maringá, Brazil 87020-900.
authors.forename: A F
authors.initials: AF
authors.lastname: Branco
authors.affiliation: Statistical Programs, College of Agricultural and Life Sciences, University of Idaho, Moscow 83844.
authors.forename: W J
authors.initials: WJ
authors.lastname: Price
authors.affiliation: Agriculture Research Division, Department of Economic Development Jobs Transport and Resources, Ellinbank Centre, Ellinbank 3821, Victoria, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Moate
authors.affiliation: Agriculture Research Division, Department of Economic Development Jobs Transport and Resources, Ellinbank Centre, Ellinbank 3821, Victoria, Australia.
authors.forename: M H
authors.initials: MH
authors.lastname: Deighton
authors.affiliation: Agriculture Research Division, Department of Economic Development Jobs Transport and Resources, Ellinbank Centre, Ellinbank 3821, Victoria, Australia.
authors.forename: S R O
authors.initials: SRO
authors.lastname: Williams
authors.affiliation: DSM Nutritional Products, Animal Nutrition & Health, Basel CH-4002, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Kindermann
authors.affiliation: DSM Nutritional Products France, Research Centre for Animal Nutrition and Health, Saint Louis Cedex, France 68305.
authors.forename: S
authors.initials: S
authors.lastname: Duval
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003612:Dairying; D004032:Diet / Q000662:veterinary*; D005260:Female; D007774:Lactation; D008697:Methane / Q000032:analysis* / Q000037:antagonists & inhibitors; D008892:Milk / Q000737:chemistry; D020005:Propanols / Q000494:pharmacology; D013459:Sulfur Hexafluoride / Q000032:analysis
chemical_list: C000603069:3-nitrooxypropanol; D020005:Propanols; D008697:Methane; D013459:Sulfur Hexafluoride
keywords: GreenFeed; dairy cow; methane; sulfur hexafluoride