Methane emissions from cattle: Estimates from short-term measurements using a GreenFeed system compared with measurements obtained using respiration chambers or sulphur hexafluoride tracer

• Published in: Animal feed science and technology 2015-05, Vol.203, p.41-52
• Main Authors: Hammond, K.J., Humphries, D.J., Crompton, L.A., Green, C., Reynolds, C.K.
• Format: Article
• Language: English
• Subjects: Dairy cattle; GreenFeed; Methane; Respiration chamber; SF6
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2015.02.008

•Average CH4 emission using GreenFeed was similar to chambers but lower than SF6.•As used here GreenFeed measurements had poor concordance with chambers.•As used here GreenFeed measurements had moderate concordance with SF6.•GreenFeed estimates of diet and animal effects were dissimilar to chambers and SF6.•The number of GreenFeed measurements, and the timing of measurements are critical. The GreenFeed (GF) system (C-Lock Inc., Rapid City, USA) is used to estimate total daily methane emissions of individual cattle using short-term measurements obtained over several days. Our objective was to compare measurements of methane emission by growing cattle obtained using the GF system with measurements using respiration chambers (RC) or sulphur hexafluoride tracer (SF6). It was hypothesised that estimates of methane emission for individual animals and treatments would be similar for GF compared to RC or SF6 techniques. In experiment 1, maize or grass silage-based diets were fed to four growing Holstein heifers, whilst for experiment 2, four different heifers were fed four haylage treatments. Both experiments were a 4×4 Latin square design with 33 day periods. GreenFeed measurements of methane emission were obtained over 7 days (days 22–28) and compared to subsequent RC measurements over 4 days (days 29–33). For experiment 3, 12 growing heifers rotationally grazed three swards for 26 days, with simultaneous GF and SF6 measurements over two 4 day measurement periods (days 15–19 and days 22–26). Overall methane emissions (g/day and g/kg dry matter intake [DMI]) measured using GF in experiments 1 (198 and 26.6, respectively) and 2 (208 and 27.8, respectively) were similar to averages obtained using RC (218 and 28.3, respectively for experiment 1; and 209 and 27.7, respectively, for experiment 2); but there was poor concordance between the two methods (0.1043 for experiments 1 and 2 combined). Overall, methane emissions measured using SF6 were higher (P