256-5 Enteric Methane Emission from Winter-Grazed Beef Cows.
See more from this Division: ASA Section: Environmental QualitySee more from this Session: General Animal Agriculture & the Environment: I
Tuesday, November 4, 2014: 3:35 PM
Long Beach Convention Center, Room 203A
The beef cowherd is responsible for over 80% of greenhouse gas emission from beef production systems and methane may be responsible for 60 – 70% of the total. Uncertainty is involved in measurement of quantities of methane from ruminants in a natural environment. Very few measurements have been made during winter grazing where cattle are not restricted by apparatus or restrained. The open path laser (OPL) method was used to measure daily methane emission from groups (18 to 25) of gestating beef cows (690 kg per cow) during mid-winter at Lacombe, AB, Canada. Lasers ran parallel to windrows of corn and triticale spaced 6.8 m apart on upwind and downwind sides. Swath length was used to ensure that allocation of forage dry matter (DM) was identical per cow-d and forage quality was approximately the same for swathed-corn and triticale. Enough forage DM was allocated for a four-day grazing period and measurement occurred for three consecutive periods on each crop. Estimates of forage DM consumption and quality were made daily. Generally, quantities of methane emitted decreased (421 – 157 g and 305 to 195 g methane per cow-d for triticale and corn, respectively) from first to fourth grazing day. Average DM per cow-d consumed was 11.0 kg for triticale and 12.7 kg for corn. Average methane emitted per cow-d using the OPL method was 261 g and 225 g for triticale and corn, respectively. This compares with the IPCC Tier 2 method for estimating methane emission based on DM intake and quality at 240 and 270 g per cow-d for triticale and corn, respectively.
See more from this Division: ASA Section: Environmental QualitySee more from this Session: General Animal Agriculture & the Environment: I