Methane from ewes and steers measured with the Laser Methane Detector correlates with open-circuit respiration chambers measurements

RICCI P; DUTHIE C-A; HYSLOP J; HOUDIJK J; ROEHE R; ROOKE J; WATERHOUSE A

Dublin

Conferencia; Greenhouse Gases in Animal Agriculture Conference; 2013

GGAA

Ruminants contribute significantly to global anthropogenic methane (CH4) emissions. As most CH4 produced by ruminants is excreted by breathing and eructation, the Laser Methane Detector (LMD) has been proposed as a method to characterise enteric CH4 emissions from animals in their natural environment. The LMD was used to measure CH4 concentration (ppm/metre) from the exhaled air of 24 lactating Scottish Mule ewes. Measurements were taken once a week during 4 weeks. Each day, LMD measurements were made during five 2-min periods per ewe at 1000, 1100, 1300, 1400 and 1500 h (P1 to P5, respectively). Ewes were fed twice a day with alfalfa pellets. The LMD was also used to measure CH4 in 72 finishing Aberdeen Angus x Limousin steers fed ad-libitum with complete diets of either 48:52 (F) or 8:92 (C) forage to concentrate ratio (DM basis). LMD measurements were made once daily during a 4 min period for 3 days while steers were in training pens, prior to chamber measurements. The LMD was used at 1 metre distance from the animal in both species. The following week ewes or steers entered to open-circuit respiration chambers (ewes in pairs) to quantify their daily CH4 output (chamber-CH4, g/d) during 48 h. In ewes, chamber-CH4 (y) was predicted best by DM intake (DMI, kg/d) and the number of eructation points (NE) in P2: y = -15.1 + 0.008*DMI + 0.493*NE (AdjR2 = 0.92, P