ALVES, A. M.

BERNDT, A.

LEMES, L. A.

OLIVEIRA, P. P. A.

PEDROSO, A. de F.

ROMERO, T. C.

The aim of this study was the evaluation of methane emissions from pure Holstein and half Jersey, half Holstein high-producing lactating cows grazing 2 different forages

LEMES, A. P.

ROMERO, L. A.

ALVES, T. C.

PEDROSO, A. M.

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J. Anim. Sci Vol. 92, E-Suppl. 2/J. Dairy Sci. Vol. 97, E-Suppl. 1 2750549		Comparison	of	active	flux	and	passive	concentration measurements of methane emissions from cattle. P. Huhtanen*1, E. H. Cabezas Garcia1, S. R. Zimmerman2, and P. R. Zimmerman2, 1Swedish University of Agricultural Sciences, Umea, Sweden, 2C-Lock Inc., Rapid City, SD.There are 2 new measurement techniques to measure emitted CH4 and CO2 from cattle in production systems, the passive concentration measurement method (PCM) and the active gas capture method (AGC). Both systems estimate cattle muzzle CH4 and CO2 emissions for short-term periods (3 to 15 min) while cattle visit a feeding station multiple times daily. The objective was to determine if the 2 techniques yielded compa-rable results under farm conditions. A GreenFeed (GF) system was used (C-Lock Inc., Rapid City, SD) that measures individ-ual animal emissions over a feed trough. For AGC, an active airflow (2000 L/min) was induced around the animal’s muzzle that attracted emissions into a air collection pipe where air-flow and CH4 and CO2 concentrations were measured and the average flux was calculated for each visit. For PCM, a concen-tration sampling intake (at 1 l/min) was placed inside the feed trough, no active airflow was used, and the average CH4 and CO2concentrations for each visit were calculated. 32 Swedish Red dairy cows (BW 664 ± 72 kg, MY 30.2 ± 6.3 kg/d, and DMI 20.1 ± 2.8 kg/d) housed in a free-stall barn had an access to 2 separate GF units. The diets were fed ad libitum as TMR (60% forages, 40% concentrates on DM basis). The GF were configured for 10-d sampling periods using PCM and AGC repeated twice. The data was analyzed with linear mixed mod-els using the MIXED procedure in SAS (SAS Inst. Inc., Cary, NC). Repeatability (R) was calculated as R = δ2Animal/(δ2Ánimal + δ2Residual). The cows visited GF on average 2.85 ± 0.95 times per day. For CH4, the between animal coefficient of variation (CV) was greater (11.0 vs. 17.6%) with PMC compared with AGC. Comparing CH4 results for individual animals to determine if ranking was consistent between AGC and PCM, a weak cor-relation was found between CH4 concentration with PCM and CH4 flux with AGC:CH4 Flux (g/d) = 363 ± 30.5 + 0.058 ± 0.0214 × CH4 (ppm; R2 = 0.13; RMSE = 52.1). For CH4/CO2 ratio, CV values were similar (6.4 and 6.6%) but averaged CH4/CO2 ratio was greater (P = 0.001) with PMC (0.107) compared with AGC (0.094). The repeatability for AGC and PCM were high (0.72 to 0.74). It is concluded that PCM methods are not sufficient for ranking animal’s emissions on farms. Measuring concentration passively is not the same as measuring fluxes.Key Words: methane, cattle, emissions0550  Methane emission intensities by Holstein and Holstein × Jersey crossbreed lactating cows in two Brazilian grazing systems. A. Berndt, A. P. Lemes,  L. A. Romero, T. C. Alves, A. M. Pedroso*,  A. D. F. Pedroso, and P. P. A. Oliveira, EMBRAPA,  São Carlos, Brazil.The aim of this study was the evaluation of methane emissions from pure Holstein and half Jersey, half Holstein high-produc-ing lactating cows grazing 2 different forages. The study was conducted at EMBRAPA’s (Brazilian Agricultural Research Corporation) experimental station located in São Carlos city, in the Southeast region of Brazil. Treatments were a combina-tion of 2 factors: 2 breeds (Holstein, HOL; and 1/2half Jersey half Holstein, JH) and 2 grazing systems (extensively grazed pastures with low stocking rate, ELS, or irrigated pastures under intensive management and high stocking rate, IHS). A total of 24 dairy cows were used (2 breeds × 2 grazing systems × 3 animals per paddock × 2 replicates), grouped according to age, stage of lactation, and level of milk production. Cows were kept on pasture and supplemented with minerals and concentrates in accordance with milk yield (1 kg of concen-trate/3 kg of milk produced). The IHS pasture was rotationally managed and both IHS and ELS were managed under variable stocking rates (“put-and-take”). Forage production and animal performance variables were measured to determine environ-mental, technical, and economic assessments. Methane emis-sion evaluation took place in May 2013 using the SF6 tracer technique. Each animal received 2 permeation tubes (average load of 1431.0 ± 76.2 mg of SF6 with an average emission rate of 1.74 ± 0.18 mg/d) 5 d before collection. Samples were collected every 24 h for 5 consecutive days. Gases were mea-sured on a Shimadzu GC 2014. Data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC) and av-erages were compared using Tukey’s test with significant dif-ferences at P < 0.05. No interactions were observed between breed and grazing system. Crossbred JH presented lower (P < 0.05) methane emission intensity than pure Holstein (11.26 ± 1.11 vs. 14.62 ± 1.11 gCH4/L milk) regardless of grazing system. Crossbreed JH cows emitted less (P < 0.05) methane per day than pure HOL (275.1 ± 20.8 vs. 337.2 ± 20.8 gCH4/d) and produced the same amount of milk (25.11 ± 1.11 vs. 23.76 ± 1.11 L/d). Efficiency of milk production can be a mitigation strategy when less methane is emitted per liter of milk.Key Words: dairy cows, emission intensity,  methane emission

Methane emission intensities by Holstein and Holstein × Jersey crossbreed lactating cows in two Brazilian grazing systems.

http://www.alice.cnptia.embrapa.br/alice/bitstream/doc/1003655/1/PATRICIA.pdf

Methane emission intensities by Holstein and Holstein × Jersey crossbreed lactating cows in two Brazilian grazing systems.

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