Repeatability and variability of short-term spot measurement of methane and carbon dioxide emissions from beef cattle using GreenFeed Emissions Monitoring System

Abstract

The purpose of this study was to determine the repeatability of methane (CH 4 ) and carbon dioxide (CO 2 ) emissions from beef cattle using GreenFeed emissions monitoring (GEM) system and as affected by sampling frequency and measurement periods. Twenty-eight crossbred replacement beef heifers were monitored using the GEM system over 59 d to collect their CH 4 and CO 2 emissions data. Heifers' feed intake was recorded by eight automated feeding stations. The standardized dry matter intake (SDMI), CH 4 and CO 2 emission and yield (g kg −1 SDMI) were averaged over 1, 3, 7, and 14 d periods. On average, animals emitted 204.7 g d −1 (SD = 36 g d −1 ) and 6408 g d −1 (SD = 780 g d −1 ) of CH 4 and CO 2 , respectively. Between-animal coefficients of variation for all variables decreased with an increasing averaging period (from 1 to 14 d). The coefficient of determination (R 2 ) between CH 4 emission and SDMI was increased from 0.25 to 0.73 as averaging period increased from 1 to 14 d. Similarly, the R 2 between CO 2 emission and SDMI increased from 0.39 to 0.79 as averaging period increased from 1 to 14 d. It was determined that averaging over 7 to 14 d with minimum of 20 spot samples was needed to produce repeatable and reliable averaged CH 4 and CO 2 emissions and correlated with SDMI.

Effect of Feeding System on Enteric Methane Emissions from Individual Dairy Cows on Commercial Farms

“…Therefore, the highest number of measurements were obtained between 17:00 to 20.59. A diurnal pattern was observed for CH 4 emissions (Table 4), which is consistent with other studies [9,14,15]. Across feeding systems, emissions were lowest between 05:00 and 08:59, which would relate to a typical time to allocate feed to dairy cows, after which emissions increased to a peak concentration between 17:00 to 20.59.…”

“…A number of studies have demonstrated techniques for obtaining measurements of CH 4 emissions from individual cattle in their normal environment using repeated spot measurements [9,[11][12][13]15,18]. The positive correlation between spot measurements of CH 4 obtained during milking and total daily CH 4 emissions by the same cows when housed subsequently in respiration chambers in a previous study [10], and the ability of the technique to detect the effect of diet [10,24], has led to considerable research into the spot measurement technique.…”

“…However, as with chambers, the SF 6 technique is not suited to sampling a large population of animals on commercial farms due to restrictions on use of gas and the attachment of equipment to animals. Recent research has focused on collecting data from commercial herds through non-invasive approaches that take repeated spot measurements whilst cattle are feeding [6,9], being milked [10][11][12], or standing [13]. Frequent sampling of gas emissions has been found to provide repeatable measurements that allow assessment of within-cow, between-cow, diet and temporal effects on CH 4 emissions.…”

“…Crompton et al [14] identified the relationship between the time of feeding and CH 4 emissions, with a rapid increase in emissions after an animal consumes food followed by a gradual decline. Several studies have observed a diurnal pattern to CH 4 emissions from ruminant livestock [9,14,15], which is affected by feed allowance and feeding frequency [14], with no overall influence on average daily CH 4 yield [16,17].…”

Methane and Carbon Dioxide Emission of Beef Heifers in Relation with Growth and Feed Efficiency

“…During the 8-12-week testing period, over 200 spot measures per heifer were obtained on average for calculating the daily gas emission rates. This amount of spot measures was well above the minimum numbers, 20 to 50, recommended by several authors [23][24][25][26] for the precise measurement of CH 4 and CO 2 with GreenFeed systems. The CH 4 averages were very similar in the two heifer populations: 205 g/d on average, while CO 2 was lower for Borculo heifers compared to Galle heifers (6139 vs. 6918 g/d) as expected, due to their lower daily gain.…”