Enteric methane and carbon dioxide emissions measured using respiration chambers, the sulfur hexafluoride tracer technique, and a GreenFeed head-chamber system from beef heifers fed alfalfa silage at three allowances and four feeding frequencies1–3

Abstract

The objective of this study was to determine methane (CH) and carbon dioxide (CO) emissions from 8 beef heifers (approximately 20 mo of age and 382 ± 24.3 kg BW) measured by respiration chambers and the sulfur hexafluoride (SF) tracer technique and a mobile head-chamber, spot-sampling system (GreenFeed; C-Lock Inc., Rapid City, SD) when fed alfalfa silage at 3 feeding levels and 4 feeding frequencies. Feeding frequency may affect CH yield (g/kg DMI), and measurement systems (such as GreenFeed or SF) are needed to obtain accurate estimates of CH emissions from individual cattle under grazing where new pasture is provided once or twice daily. The Hereford × Friesian heifers were used in 5 consecutive periods (P1 to P5) of 14 d with CH and CO emissions measured with the SF technique in wk 1 (5-6 d), with chambers in wk 2 (2 d), and with the GreenFeed system when not in chambers (8 d) of each period. Alfalfa silage was restricted to 6, 8, 8, and 8 kg DM/d in P1, P2, P3, and P4, respectively, and provided ad libitum (10.9-12.2 kg DM/d) in P5. Silage was fed in 2, 2, 3, and 4 meals per day in P1, P2, P3, and P4, respectively, and was continuously available (refilled twice daily) in P5. Methane production increased from 141 to 265 g/d as DMI doubled ( < 0.001), but average CH yields measured in respiration chambers (24.5 g/kg DMI) and by the SF technique (22.8 g CH/kg DMI) and the GreenFeed system (26.2 g/kg DMI) were unaffected by feeding management ( = 0.6 for chambers and SF and = 0.06 for GreenFeed). The CH yields estimated by the GreenFeed system did not differ from CH yields estimated by the chambers in P1, P2, P3, and P5 but were greater ( < 0.02) than CH yields estimated by the SF technique in P2, P3, P4, and P5. Yields of CO (g/kg DMI) decreased with increasing DMI ( < 0.04) and CO production (g/d) increased from 5,293 to 9,167 g/d as DMI increased ( < 0.001). In general, the SF technique and the GreenFeed system provided means for CH yield that were not different from those of respiration chambers, and CH yields (g/kg DMI) were unaffected by DMI level or feeding frequency.

Genetic control of methane emission, feed efficiency and metagenomics in dairy cattle

“…The GreenFeed system has been compared to RC and has shown mixed results for agreement, with poor concordance (CCC = 0.1) in dairy cattle but high concordance in beef cattle (CCC = 0.84) . In most studies, the accuracy was not significantly different from that of the RC, but the GreenFeed had higher variation and was less precise Jonker et al, 2016;Rischewski et al, 2017). Typical sources of imprecision for the GreenFeed include the duration and number of visits.…”

“…Visitation to the unit is voluntary and requires training and adaption to the unit. Daily CH 4 emissions (g/d) are estimated using volumetric airflow rate adjusted to standard temperature and pressure in a manner analogous to respiration chambers Jonker et al, 2016):…”

“…Some studies report as few as 1.3 -2.6 visits per animal per day and failed to detect diurnal variation or treatment effects with the GF which were detected with other methods Arthur et al, 2017). Conversely, other studies report 3.4 -4.4 visits per animal per day and detected significant treatment and diurnal variations (Jonker et al, 2016;Waghorn et al, 2016). The number and duration of visits need to be considered when estimating daily CH 4 production in order to account for diurnal variations.…”

“…The number and duration of visits need to be considered when estimating daily CH 4 production in order to account for diurnal variations. Some studies have used weighted average as in equation 3 above (Jonker et al, 2016), whilst others have used a moving average (Arbre et al, 2016;Arthur et al, 2017) or modelled repeated measures using statistical methods (Arthur et al, 2017). Thus, careful control is required of the operator to ensure adequate visitation to the unit and timing of the visits to ensure adequate statistical power of the method.…”

Intensidades de emissão de gás metano de bovinos Nelore terminados a pasto e cruzados em confinamento

“…As câmaras respirométricas foram pioneiras e de grande importância para estudos com emissão de gases, e também exigências energéticas dos animais, gerando as primeiras informações para a elaboração das tabelas do NRC (NRC, 2001 as vantagens e desvantagens entre eles (BHATTA et al, 2007;DOREAU et al, 2018;DORICH et al, 2015;HAMMOND et al, 2015;HRISTOV et al, 2016;JONKER et al, 2016;MCGINN et al, 2006;OSS et al, 2016;PINARES-PATIÑO;CLARK, 2008;STORM et al, 2012;TROY et al, 2016).…”