A stream tracer technique employing ionic tracers and specific conductance data applied to the Maimai catchment, New Zealand

2005 ◽  
Vol 19 (13) ◽  
pp. 2491-2506 ◽  
Author(s):  
Michael N. Gooseff ◽  
Brian L. McGlynn
Keyword(s):  
New Zealand ◽  
Specific Conductance ◽  
Tracer Technique ◽  
Conductance Data

Methane emissions from young and mature dairy cattle

2016 ◽  
Vol 56 (11) ◽  
pp. 1897 ◽  
Author(s):  
C. A. Ramírez-Restrepo ◽  
H. Clark ◽  
S. Muetzel
Keyword(s):  
New Zealand ◽  
Emission Factor ◽  
Dry Matter ◽  
Sulfur Hexafluoride ◽  
Dry Matter Intake ◽  
Tracer Technique ◽  
Ch4 Emissions ◽  
Dairy Heifers ◽  
Age Related ◽  
The Mean

Daily methane (CH4) emissions (g) and CH4 yield (g/kg dry matter intake) were measured from 10 dairy heifers (<1 year old) and nine rumen-fistulated cows (>6 years old) fed ryegrass (Lolium perenne) chaffage indoors. The CH4 emissions were estimated using the sulfur hexafluoride tracer technique in four ~5-day periods beginning in June 2008 and repeated 4, 6 and 7 months later. Respiratory chambers were used in four ~13-day periods beginning in November 2008 and repeated 2, 5 and 6 months later. Third and fourth sulfur hexafluoride tracer periods overlapped with the first and second chamber measurement periods, respectively. Averaged over the four measurement periods the CH4 yields determined using both techniques were similar for heifers and cows. The mean CH4 yield estimated by the sulfur hexafluoride tracer technique was 25.3 ± 0.52 for heifers and 24.1 ± 0.55 for mature cows, whereas the mean CH4 yield measured in respiratory chambers was 23.7 ± 0.66 for heifers and 23.6 ± 0.66 for mature cows. Averaged over the eight measurements irrespective of technique, CH4 yields for heifers (24.5 ± 0.42) and cows (23.8 ± 0.43) were similar. There was also no difference between CH4 methods for assessing CH4 yield during the overlapping measurement periods. It was concluded that no consistent differences in CH4 yield existed between heifers and mature cows. Therefore, we do not recommend adoption of an age-related emission factor for cattle in the national inventory calculations for New Zealand.

Methane emissions from grazing Jersey×Friesian dairy cows in mid lactation

2008 ◽  
Vol 48 (2) ◽  
pp. 230 ◽  
Author(s):  
A. Cavanagh ◽  
L. McNaughton ◽  
H. Clark ◽  
C. Greaves ◽  
J. M. Gowan ◽  
...  
Keyword(s):  
New Zealand ◽  
Dairy Cows ◽  
Dry Matter ◽  
Sulfur Hexafluoride ◽  
Methane Emissions ◽  
Tracer Technique ◽  
Dilution Technique ◽  
Ad Libitum ◽  
Tracer Dilution ◽  
Clover Pasture

As part of a large quantitative trait loci trial, methane emissions were measured on 698 second and third lactation dairy cows which were the progeny of six bulls. The trial ran over two 4-week periods in January 2004 and 2005. Methane samples were collected over 24 h on each of four consecutive days in 2004 and three consecutive days in 2005. Methane emissions were measured using the sulfur hexafluoride (SF6) tracer dilution technique. During measurement periods, all cows grazed grass–clover pasture with ad libitum herbage allowances. Herbage dry matter intakes (DMI) were calculated using Australian Feeding Standards based on individual cow data of milk yield, liveweight, liveweight change and cow body condition. The average DMI was estimated to be 17.1 kg/day (s.d. = 2.0). Daily methane emissions ranged from 151 to 497 g/day with an average of 311 g/day (s.d. = 43.8) or 18.2 g/kg DMI (s.d. = 2.8); this is 15.7% lower than the figure currently used in the New Zealand national inventory. This study also indicates that there are large differences between cows in methane emissions per kg DMI when estimated using the SF6 tracer technique.

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