First measurements of methane emitted by grazing cattle of the Argentinean beef system

Abstract We report the first measurements of methane emitted by cattle of the Argentinean beef system, one of the largest in the world. Special care was taken to keep the animals under production conditions typical of the Pampa, the main livestock region of the country. Therefore, we applied the SF6 tracer technique to 20 young Aberdeen Angus steers randomly chosen in a commercial farm, in which paddocks they were left to graze. The live‐weight change of the animals, the herbage allowance and quality were followed during the research. The magnitudes varied significantly throughout the experiment (which included two separate periods of time, the first during December 2005 and the second in February‐March 2006) and from paddock to paddock. In spite of these differences, the average daily methane emissions per head rarely depart from 170 g/day However, larger variations were observed in the methane yield and, specially, in the methane em itted per weight gained. The work was also useful to analyse some techn...