Extending the Collection Duration of Breath Samples for Enteric Methane Emission Estimation Using the SF₆ Tracer Technique.
The daily sample collection protocol of the sulphur hexafluoride (SF₆) tracer technique for the estimation of methane (CH₄) emissions from ruminants may not be practical under extensive grazing systems. Here, under controlled conditions, we evaluated extended periods of sampling as an alternative to daily sample collections. Eight rumen-fistulated cows were housed and fed lucerne silage to achieve common daily feed intakes of 6.4 kg dry matter per cow. Following SF₆ permeation tube dosing, eight sampling lines were fitted to the breath collection harness, so that a common gas mix was available to each line. Half of the lines collected samples into PVC yokes using a modified capillary system as commonly used in New Zealand (NZL), and half collected samples into stainless steel cylinders using a ball-bearing flow restrictor as used in Argentina (ARG), all within a 10-day time frame, either daily, across two consecutive 5-day periods or across one 10-day period (in duplicate). The NZL system had greater sampling success (97.3 vs. 79.5%) and yielded more consistent CH₄ emission estimates than the ARG system. Emission estimates from NZL daily, NZL 5-day and NZL 10-day samplings were 114, 110 and 111 g d(-1), respectively. Extended sample collection protocol may be feasible, but definitive evaluation of this alternative as well as sample collection systems is required under grazing situations before a decision on recommendation can be made.
Grasslands Research Centre, AgResearch Limited, Palmerston North 4442, New Zealand. cesar.pinares@agresearch.co.nz.
César
C
Pinares-Patiño
Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, Tandil 7000, Buenos Aires, Argentina. jgere@exa.unicen.edu.ar.
José
J
Gere
Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, Tandil 7000, Buenos Aires, Argentina. kwilliams@exa.unicen.edu.ar.
Karen
K
Williams
Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, Tandil 7000, Buenos Aires, Argentina. rgratton@rec.unicen.edu.ar.
Roberto
R
Gratton
Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, Tandil 7000, Buenos Aires, Argentina. pjuliarena@exa.unicen.edu.ar.
Paula
P
Juliarena
Grasslands Research Centre, AgResearch Limited, Palmerston North 4442, New Zealand. german.molano@agresearch.co.nz.
German
G
Molano
Grasslands Research Centre, AgResearch Limited, Palmerston North 4442, New Zealand. sarah.maclean@agresearch.co.nz.
Sarah
S
MacLean
Grasslands Research Centre, AgResearch Limited, Palmerston North 4442, New Zealand. edgar.sandoval@agresearch.co.nz.
Edgar
E
Sandoval
Grasslands Research Centre, AgResearch Limited, Palmerston North 4442, New Zealand. grant.taylor@agresearch.co.nz.
Grant
G
Taylor
Grasslands Research Centre, AgResearch Limited, Palmerston North 4442, New Zealand. john.koolaard@agresearch.co.nz.
John
J
Koolaard
SF6 tracer; breath collection; cattle; collection duration; methane