Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/15/2004
Publication Date: 2/8/2005
Citation: Harper, L.A. 2005. Methane emissions from grazing and feedlot cattle: measurement, treatments,and results [abstract]. Society for Rangeland Management 58th International Annual Meeting, Fort Worth, Texas. February 7-11, 2005.
Technical Abstract: Methane is believed to contribute about 18% of the global-integrated radiative forcing and methane emissions from enteric fermentation is thought to represent about 16 % of anthropogenic emissions. Three micrometeorological techniques were developed to measure, with minimal disturbance, methane production by cattle in pasture and feedlot conditions. An integrated horizontal flux (IHF) technique was developed to measure emissions from a small number of animals (less than six). This technique is accurate and can be verified using tracer-released gases. A modification of the IHF technique using open-path laser spectrometry was developed to measure emissions from an intermediate number (10 to 25) of cattle. Similarly, this technique may be verified using released methane as a tracer gas. For measurement of methane emissions from a large number of animals (50 to 100,000 animals), a dispersion analysis technique was developed [backward Lagrangian stochastic analysis (bLS)] for remotely determining trace-gases including methane, ammonia, and other gases. Results of feedlot animals showed similar enteric emissions using both the IHF and bLS techniques. Comparisons between animals treated and non-treated with methane-production inhibitors showed significant reductions of enteric emissions. The use of non-interference techniques to evaluate enteric emissions under field conditions has shown these emissions to be smaller than previously thought.