METHANE AND CARBON-DIOXIDE EMISSIONS FROM DAIRY-COWS IN FULL LACTATION MONITORED OVER A 6-MONTH PERIOD

Methane and CO2 emissions from a herd of 118 lactating cows were measu red directly by continuous monitoring with an infrared gas analyzer fr om 24 gas sampling locations. A total of 112 d of gas output was recor ded between June 1993 and November 1993. Recordings were integrated at .5-h intervals, so that there were 48 data points for each 24-h perio d. The mean 24-h CH4 emission per cow was 587 +/- 61.3 L; the range wa s 436 to 721 L. The mean 24-h CO2 emission per cow was 6137 +/- 505 L, and the range was 5032 to 7427 L. These values were not corrected for gas emissions from stored manure, which contributed 5.8 and 6.1%, res pectively, to CH4 and CO2 output under conditions of this experiment.