ALARI, F. O.

FRIGHETTO, R. T. S.

KOURY FILHO, W.

LEMOS, N. L. S

MALHEIROS, E. B.

MEISTER, N. C.

RUGGIERI, A. C.

SILVA, V. C.

Repository Open Access to Scientific Information from Embrapa

541Determination of methane production on grass fed goatsN C Meister1, N L S Lemos1, F O Alari1, V C Silva1, W Koury Filho2, E B Malheiros1, R T S Frighetto3, A C Ruggieri11Universidade Estadual Paulista Julio de Mesquita - UNESP, Jaboticabal/SP, Brazil, 2BrasilcomZ - Zootecnia Tropical,Jaboticabal/SP, Brazil, 3Embrapa - Meio Ambiente, Jaguariuna, Brazil Email:naomi@brasilcomz.comIntroduction Methane emissions from cattle are already known, but for goats that value is still estimated (IPCC, 2006).Around the world, the number of goats is estimated on 910 million head, mostly are raised on pasture. To measure themethane production from animals under grazing conditions, the sulfur hexafluoride (SF6) tracer technique is consideredappropriate for cattle.This study aimed to adapt the SF6 technique to use in small ruminants, and measure the methane (CH4) emission in goatsunder grazing conditions.Material and methods Two experiments were performed. The first was to adapt the SF6 tracer technique, described byJohnson et al. (1994) for measure in goats and the second had the objective of quantifying the emission of CH4 from theseanimals. The first study we used one adult male weighing 78.5 kg, under generous grazing conditions to test adaptations.The major adjustments were: making collector cylinders with a capacity of 2 liters, although smaller, and the change ofposition from the neck to the back of the animal with the aid of an apparatus similar to a saddle, so not to adversely affectthe movements and access to food (Figure 1). Another important test was related to the emission rate of tracer gas capsules,on which were evaluated, in the animal, two emission rates (622 and 1217 ng / min.). For each emission rate, four samplesof methane eructed by the animals were collected. Concentrations of CH4 and SF6 in the collection cylinders were measuredby gas chromatography, for such the cylinders were positively pressurized with N2 and connected directly into thechromatograph (Agilent ® Model 6890). From the known rate of clearance of the tracer gas in the rumen, andconcentrations of methane and trace gas in gas samples captured, the methane release by the animals were calculated. Inorder to quantify the methane emissions the second trial was initiated with five goats, adult females of the Anglo Nubianbreed, with an average weight of 54.4 kg under intermittent stocking, grazing for 11 hours in areas formed with Panicummaximum cv. Tanzania, with ad libitum access to water and mineral salt, being gathered into the fold at night.Based on the results of the first experiment, the capsules introduced into the rumen were in the range of 500 to 1,000ng/min. emission of SF6. The pre evacuated collector cylinders (-12.00 to -12.60 psi) were placed in the animals at 7ambefore releasing them in the grazing area and changed every 24 hours. The collections were made for six consecutive days.The statistical analyses in experiment 1 was the Pearson's correlation between CH4 and CF6 concentration, and inexperiment 2 the GLM procedure was used to test the model, and the Student Newman Keuls Test to analyze the averagesconsidering 5% of probability.Results In experiment 1, the average CH4 emission was 1.4 ± 0.2 and 1.2 ± 0.1 g/day/metabolic body weight (bodyweight0.75) for emission rates 622 and 1217 ng/min. respectively. Highest correlation was observed between theconcentrations of SF6 and CH4 in the samples taken when the animal received the capsule with emission of 622 ng/min. (r =0.99) when compared with the rate of 1217 ng/min (r = 0.41). In the second experiment the average CH4 emission was17.59 g/day/animal or 0.88 g/day/ metabolic weight for the goats used in the experiment, corresponding to 0.91 g/day or 5.3kg/year in 40 kg goats.Conclusions After adjustments, the SF6 methodology was considered adequate for measuring methane emission on grassfed goats. The emission of methane per kg of metabolic body weight of 0.91 g/day or 5.3 kg/year for 40 kg goats can beused as reference in grazing goats. This value is close to the one estimated by IPCC of 5 kg/year.Acknowledgements The authors gratefully acknowledge funding from FAPESPReferences Johnson, K.A; Huyler, M.T.; Westberg, H.H.; Lamb, B.K.; Zimmerman, P. Environmental Science andTechnology. 1994, 28, 359-362; DOI 10.1021/es00051a025.IPCC: Revised IPCC. Cambridge: University Press, 2006.

Determination of methane production on grass fed goats.

http://www.alice.cnptia.embrapa.br/alice/bitstream/doc/982552/1/2013RA045.pdf

Determination of methane production on grass fed goats.

Abstract

Similar works

Full text

Available Versions

Repository Open Access to Scientific Information from Embrapa