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Emission of GHG from livestock production in Japan
International Congress Series 1293 (2006) 13 – 20
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Emission of GHG from livestock production in Japan Junichi Takahashi * Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, Japan
Abstract. Methane (CH4) and nitrous oxide (N2O) are main GHG emitted from livestock production. In the estimation based on dry matter intake, total emission from enteric fermentation is 0.375 million tons annually in Japan. Animal effluent which is another source of methane from animals corresponds to 22.7% of total amount of methane emission. Total emission of N2O–N from animal effluent in Japan was estimated to be 8.7867Gg year 1. According to the IPCC report (1995), the total N2O–N emission is estimated 1500Gg year 1 in the world. Thus, N2O emission from Japanese animal agriculture accounts 0.59% in the global emission. As 0.717 Tg nitrogen year 1 have been excreted from the livestock in Japan, the excretion accounts 0.71% in 101 Tg year 1 of total nitrogen excretion from the livestock. Relatively lower nitrogen excretion as N2O can be calculated in Japan. D 2006 Elsevier B.V. All rights reserved. Keywords: Greenhouse gas; Methane; Nitrous oxide; Ruminant; Biogas; Kyoto protocol
1. Introduction The gases which bring greenhouse effect are water vapor and trace gases in atmosphere, a carbon dioxide (CO2) methane, chlorofluorocarbon (CFC-11,12) and nitrous oxide. The problem as greenhouse gases is an increase in the trace gases in the atmosphere such as CO2. The total emission of greenhouse gases including methane in 1997 was 8.5% higher than the level in 1990. In the 3rd session of the Conference of Parties to the United Nations Framework Convention on Climate Changes held in Kyoto December 1997, Japan owed the obligation to decrease by 6% of the total greenhouse gases emission in 1990 until 2008 to 2012 (Kyoto Protocol, 1997). Japan concluded the Kyoto Protocol on June 4, 2002. As of February 2, 2005, 140 countries and EU have concluded it now. The coming into effect requirement was filled by the conclusion of Russia, and the Kyoto Protocol effectuated on February 16, 2005. The
* Tel./fax: +81 155 49 5421. E-mail address: [email protected]. 0531-5131/ D 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2006.02.043
14
J. Takahashi / International Congress Series 1293 (2006) 13–20
reduction of greenhouse gas emission is a global issue. CO2 occupies about the half of the entire greenhouse effect, and CH4 is greenhouse gas succeeded to CO2 [1]. The concentration of atmospheric CH4 is only 2 ppmv or less and slighter than 350 ppmv of carbon dioxide. An increase in CO2 is largely originating in the combustion of the fossil fuel according to the development of the ore industry in advanced nations after the Industrial Revolution. As CH4 is removed reacting with radical OH of the troposphere, the longevity of CH4 (12–17 years) in atmosphere is shorter than 50–200 years of CO2 [2]. The concentration of atmospheric methane at present is twice of the value before the Industrial Revolution. The annual rise of the concentration has shown a rapid increase of 1.0–1.3% in the last decade compared with 0.5% of CO2. However, the absorptivity of infrared rays is already near saturated because a large amount of CO2 exists in atmosphere and only absorption increases around a big absorption zone at 16Am wavelength. Even if the concentration increases, the absorption ability of infrared ray in CO2 does not change so much. As for CH4, the relative absorptivity of the farinfrared radiation is large (about 21 times CO2 for each molecule, and 58 times in the weight ratio) and absorptivity is not saturated like CO2. The absorptivity of the far-infrared radiation in methane rises proportionally to the temperature rise. Most of absorption zones of methane are in 8–13Am that do not overlapped the absorption zones of water vapor and CO2. Therefore, even a little increase of methane concentration in atmosphere exerts extremely strong effect on global warming. It is possible to divide the sources roughly into a natural source and an anthropogenic source though the source includes many things. The annual emission of CH4 in the atmosphere accounts for 535 Tg according to the report of IPCC (Intergovernmental Panel on Climate Change) in 1994 [3]. The 85Tg derived from the rumen fermentation of the ruminant animals. When the methane emission of 25 Tg from animal waste includes in the calculation, methane emission from ruminants occupies 20% of total emission. This is one of big sources as well as marsh (wetland) 115Tg. Sixty percent or more of the amount of methane production is directly attributed to human activities. The enlargement of rice paddy (60 Tg) and livestock is almost proportional to the expansion of human population. This may be the main cause of an increase in CH4 in atmosphere. CH4 produced by rumen fermentation of ruminant animals is emitted into atmosphere by eructation. On the other hand, the main anthropogenic sources of N2O are from agriculture and animal agriculture. Though there are some difficulties in the quantitative assessment of casual relation between nitrogen applied as fertilizers or composts and N2O emission, 0.01–2.0% of applied nitrogen is estimated to convert to N2O. The present paper deals with current situation of GHG emission from livestock production in Japan. 2. Methane emission of enteric fermentation of farm animals The ruminant species is a big group which contains wild kinds of the giraffe and deer families, etc. including bovine, and even only the Bos. sub-family is classified into five genera and 14 species. Target one for the control is milking cow and domesticating beef cattle. The amount of the CH4 emitted by eructation from lactating cow is presumed to be 200–400 l/day though 1,200,000,000 domestic cattles are raised on the earth. One or two drum cans equivalent of pure methane will be emitted into the atmosphere by milking one cow every day.
J. Takahashi / International Congress Series 1293 (2006) 13–20
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Fig. 1. Methane emission from rumen fermentation from ruminant farm animals. Live body weights of cattle and buffaloes were assumed to be 600 kg. Methane emission was estimated from 80 ml kg 0.75 body weight h 1.
Fig. 1 shows methane emission from rumen fermentation from cattle and buffalo calculated from animal numbers. The calculation is based on live body weights of cattle and buffaloes which were assumed 600 kg and methane emission was estimated from 80 ml kg 0.75 body weight h 1. Fig. 2 shows the methane emission from small ruminants. The calculation is based on live body weights of sheep and goats which were assumed 50kg and methane emission were estimated from 65 ml kg 0.75 body weight h 1. Table 1 shows estimated methane emission from enteric fermentation of farm animals in Japan based on DMI. Total emission from enteric fermentation is 0.375 million tons annually. 100 drum cans of 100% CH4 will be emitted there into an atmosphere everyday if dairy farmer keeps 100 lactating cow in his farm. Although CH4 is combustible, there is no example of happening of the explosion accident because about 100 times are diluted with the expiration. In other words, it should be impossible to recycle CH4 emitted through eructation as a combustible energy resource, and control the quantity of production in the rumen from the viewpoint of the prevention of global warming. The mechanism of methane production in the rumen and its biological significance are discussed as follows. Ruminant animals such as cattle, sheep and goat have reticulo-rumen that produce good quality proteins of milk and meat, and offer human from the low-quality
Fig. 2. Methane emission from rumen fermentation from small rumen. Live body weights of sheep and goats were assumed to be 50 kg. Methane emission was estimated from 65 ml kg 0.75 body weight h 1.
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J. Takahashi / International Congress Series 1293 (2006) 13–20
Table 1 Estimated methane emission from enteric fermentation of livestock in Japan based on DMI Animals Dairy cow Lactating Dry Replacing Beef cattle Reproducing Fattening JB(N1 year) (b1 year) HF Sheep and goat Pig Horse Total
DMI (kg)
CH4 production (l day 1 head 1)
15.8 7.5 7.9
446.5 255.4 267.3
5.8
201.9
7.3 5.2 9.5 0.8 4.2
249.3 181.8 312.2 15.9 69.0
No. of animals
CH4 emission (Tg year 1)
1,904,875 1,082,000 332,230 490,575 2,292,700 696,450
0.182 0.126 0.022 0.034 0.150 0.037
565,000 226,550 804,750 66,000 11,335,000 24,000 15,623,675
0.037 0.011 0.066 b0.001 0.012 b0.001 0.345
Source: Shibata [4].
biomass resources like grasses which cannot be used directly as human foods. Carbohydrate in roughage such as grasses is cell wall constituent, cellulose and hemicellulose. These structural carbohydrates cannot be decomposed by animal’s digestive enzymes (Photo 1). Reticulo-rumen means rumen and reticulum which take part in rumination. These dietary fibers efficiently receive various bacterial digestion with the enzymes secreted from cellulolytic bacterial cells in the huge capacity (200 l) of rumen (Fig. 3). Then the decomposed mono-saccharide receives the fermentation action in the bacterial cells. The fermentation product is volatile fatty acids such as acetic acid. These VFAs are energy sources or substrates of body fat and bacteria and protozoa which proliferate by these fermentation processes and are used for the host animals to maintain and to produce as microbial protein. This digestion and the fermentation process by this microorganism is indeed a clever device.
Photo 1. Scanning electron microscopy of bacterial digestion of fibrous fraction in the rumen.
J. Takahashi / International Congress Series 1293 (2006) 13–20
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Fig. 3. Bacterial digestion and fermentation of feed fibers in the rumen.
Besides the digestion of fibers, essential amino acids, vitamin B group and K are synthesized under usual feeding condition. This microbial metabolism does a large contribution to human nutrition through animal nutrition. However, H2 and CO2 are produced when fibers are digested and fermented by the rumen bacteria. Consequently, a huge amount of CH4 is produced with methanogenic archaea in the rumen expressed by the simple reaction: 4H2+CO2YCH4+2H2O. However, this methanogenic pathway by CO2 reduction is a complex system, and seven steps of enzymic reactions involve in the reduction. As H2 obstructs the proliferation of useful bacteria in the rumen, methanogenic archaea has the role as a scavenger of this H2 in the rumen, and is useful for the homeostasis of the rumen ecosystem. In general, the amount of CH4 produced is large in feed and high in fiber content. However, the main substrate of the methane is digestible structure carbohydrates (cell wall constituents) such as hemicellulose. Therefore, it is demonstrated in sarcasm that forages rich in digestible fibers to make a performance of ruminant animals result in large emission of methane. It is the most difficult point for this contradiction to think about the control of the methane generation in the rumen. CH4 is a combustible gas with the calorie of 892.6 kJ (25 8C, 1013hPa) per mole and loss of the feed energy is estimated 7–10%. Recently, attention is paid to the CH4 emission problem from ruminant animals by the point of environmental problems rather than an economical aspect of the energy metabolism. Methanogenic archaea is classified into 12 genera, and some kinds of important archaea have been isolated in the rumen. These methanogenic archaea are Gram-positive strict anaerobe. They are cocobacilli about 0.7Am wide and 1.8 Am in length and non-motile spheres with 1.5–2.0 Am in diameter which forms big clusters. Since 20% of rumen methanogenic archaea is parasitic on the surface of protozoan body (Photo 2). The decrease in the CH4 generation is clarified by defaunation (removal of protozoa). Excess feeding of concentrate mixture such as cereals exerts the influence on protozoa. In consequence, methanogenesis may decline. This is a reality in a modern high performance
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J. Takahashi / International Congress Series 1293 (2006) 13–20
Photo 2. Some species of methanogen associated with ciliate protozoa. 20% methanogen may be endosymbionic.
cow milking and beef cattle feeding. However, for consolidated milk cow at the present age which pursues high-ranking production and meat, a negative side of frequent incidence of metabolic diseases such as lactic acid acidosis and the displaced abomasum etc. has come to light. Moreover, the adverse effect of H2 is not removed in this case. As for the removal of H2 by a strong reduction reaction, the effect is highest in the CO2 reduction obstruction. Ruminal reduction of nitrate contained in the forage plants shows a remarkable effect of control in the ruminal CH4 generation. When the nitrate intake is too large, the subclinical poisoning of nitrate is takes place. Moreover, approval ionophores such as monensin, salinomycin are known as propionate enhancers the propionic acid by the antibiotic which has been put to practical use, and the suppressing effect of these antibiotics to on rumen methanogenesis. However, there are some anxieties due to appearance of a resistant bacteria by the long-term use, remaining in the products, and shifted anxiety to the human body. Additionally, though the control effect on rumen methanogenesis is reported as for the halogen compounds or saturated and unsaturated fatty acids, there are some adverse effects on the fiber digestion problem as the chronic poisoning. Therefore, practical use of these compounds is not shown. In other words, to control only the rumen CH4 production without adverse effect on the useful bacteria in the rumen and the manipulation method must be safe for animal and human bodies and environment. In Japan, the effects of various probiotics, the plant extracts and a sulfur containing amino acid are being examined as feed additives of a natural material which suits these conditions now [5]. On the other hand, animal effluent which is another source of methane from animals corresponds to 22.7% of total amount of methane emission. This CH4 can be recycled as an energy resource by the anaerobic fermentation processing. Table 2 shows estimated methane emission (Gg year 1) from animal effluent in Japan. Rapid development of animal agriculture industry in Japan has resulted in a remarkable imbalance between the increased amount of animal effluents and cultivated land area to apply them. An absolute shortage of land area to produce animal feed and animal production highly dependent on imported ingredients of concentrates has amplified the imbalance. The research of the plant level has been advanced in the Europe dairy farming countries such as Denmark and Germany, and the CH4 energy from the domestic animal
J. Takahashi / International Congress Series 1293 (2006) 13–20
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Table 2 Estimated methane emission (Gg year 1) from animal effluent in Japan Dairy cow Manure Drying Biogas Composting Combustion Urine Biogas Sludge process Accumulation Slurry Drying Biogas Composting Accumulation Total
Beef cattle
Pig
Laying hen
Broiler
Total
0.0065 0.0415 5.3526 0.0160
0.0040 0.0061 0.6316 0.0044
0.0075 0.1335 0.8415 0.0240
0.0439 0.1228 0.8877 0.0920
0.0093 0.0825 1.0956 0.2560
0.0676 0.3864 8.8090 0.3924
0.0001 0.0000 0.1417
– – 0.0082
0.0008 0.0000 0.1104
– – –
– – –
0.0009 0.0000 0.2603
0.00730 0.06200 0.57090 6.94600 13.14460
0.0125 0.1613 7.1577 0.1656 8.1478
0.0029 0.0275 0.2508 0.8096 2.2085
– – – – 1.1464
– – – – 1.4434
0.0227 0.2508 0.0000 7.9212 26.0907
Source: Haga [6].
excreta has already been made the capital at the stage of practical use. In Japan these researches have just started. Animal effluent cause not only the stink problem but also the eutrophic pollution problem of the lake, pond, river and the sea water by nitrate nitrogen which derives from ammonia nitrogen. In addition, because nitrous oxide (N2O) which is derived from ammonia becomes another greenhouse gas, and becomes the cause of acid rain, too, animal effluent processing is a world issue. Some EU countries have legislation to maintain a severe restriction method for animal effluent processing. That is, the control of the CH4 emission from animal is a big problem which includes the control of the CH4 Table 3 Estimated nitrous oxide emission (N2O–N Gg year 1) from animal effluent in Japan Manure Drying Biogas Composting Combustion Urine Biogas Sludge process Accumulation Slurry Drying Biogas Composting Sludge process Accumulation Total Source: Haga [6].
Dairy cow
Beef cattle
Pig
Laying hen
Broiler
Total
0.0064 0.0390 0.3825 0.0001
0.0004 0.0050 0.0392 0.0000
0.0156 0.2603 0.1245 0.0004
0.1920 0.5040 0.2760 0.0032
0.0672 0.0428 0.5618 0.0146
0.2816 0.8511 1.3840 0.0183
0.0038 0.1080 0.2445
0.0027 0.0096 0.0267
0.0375 2.7600 0.1725
– – –
– – –
0.0440 2.8776 0.4437
0.0116 0.0930 0.0653 0.0240 0.28350 1.26170
0.0172 0.2093 0.7050 0.0000 0.0060 1.0211
0.0112 0.0998 0.0690 1.2120 0.0795 4.8423
– – – – – 0.9752
– – – – – 0.6864
0.0400 0.4021 0.8393 1.2360 0.3690 8.7867
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fermentation in the rumen, the promotion of anaerobic fermentation of effluents to capture methane and use of the residue after fermentation as a fertilizer. Furthermore, an efficient conversion of methane energy remains to be elucidated for recycling. Not only the animal husbandry of one country but also all over the world correspondence is urged to contribute to the global warming prevention by the solution of these problems. 3. Nitrous oxide emission from animal effluent Table 3 shows estimated nitrous oxide (nitrogen basis) emission (Gg year 1) from animal effluent in Japan. Total emission of N2O–N from animal effluent in Japan was estimated to be 8.7867 Gg year 1. According to the IPCC report (1995) [7], total N2O–N emission is estimated 1500Gg year 1 in the world. Thus, N2O emission from Japanese animal agriculture accounts 0.59% in the global emission. As 0.717Tg nitrogen year 1 has been excreted from livestock in Japan, the excretion accounts 0.71% in 101Tg year 1of total nitrogen excretion from livestock. Relatively lower nitrogen excretion as N2O can be calculated in Japan. In Japan, however, excess amount of the untreated effluent resulted in contamination of high nitrate in underground water and pathogens such as cryptosporidium in surface water. The complaints to the pollution problems in animal agriculture industry have been increased as the drastic expansion of animal population in limited areas. The issues which should be resolved are the developments of various technologies for animal effluent management to control offensive odors and wastewater, and feeding management to reduce the excretion of nitrogen and phosphorus. For the exploitation of energy through anaerobic fermentation of animal manures and organic wastes, biogas plant is spreading gradually in animal industries in Japan. Many research projects have been carried out to withdraw the energy of methane in the process related to animal and organic effluent management. The fuel cell which uses animal effluents and organic wastes became actual ones depending upon the advancement of desulfurization technology such as biodesulfurization. Promoting the environmentally conscious agriculture which does not rely on the chemical fertilizer can be realized by solving issues on excess nitrogen problem and creation of recycled energy from animal effluent and organic wastes in animal agriculture. References [1] F. Peace, Methane: the hidden greenhouse gas, New Scientist 122 (1663) (1989) 37 – 41. [2] A.R. Moss, Methane, 1993, Chalcombe Publications, Kingston, pp. 23 – 47. [3] Intergovernmental Panel on Climate Change (IPCC), in: J.H. Houghton, L.G. Meria Filho, J. Bruce, Hoesung Lee, B.A. Callander, H. Haites, N. Harris, K. Maskell (Eds.), Climate Change 1994, Cambridge University Press, NewYork, 1994, pp. 25 – 27. [4] M. Shibata, et al., Estimation of methane production in ruminants, Anim. Sci. Technol. (Jpn) 64 (1993) 790 – 796. [5] J. Takahashi, et al., Modification of methane emission in sheep by cysteine and a microbial preparation, Sci. Total Environ. 204 (1997) 117 – 123. [6] K. Haga, Control of greenhouse gases emission (Jpn.), in: Reports on the Working Group for the Technology of Greenhouse Gases Control in Animal Husbandry, vol. 3, 1998, pp. 72 – 97. [7] Intergovernmental Panel on Climate Change (IPCC), Climate Change 1995: Impacts, adaptations and mitigation of climate change: scientific–technical analyses, in: R.T. Watson, M.C. Zinyowera, R.H. Moss (Eds.), Contribution of Working Group II to the Second Assessment of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambrige, 1995, pp. 747 – 771. Available from Cambridge.
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Emission of GHG from livestock production in Japan Junichi Takahashi * Department of Animal Science, Obihiro University of Agriculture and Veterinary Medicine, Japan
Abstract. Methane (CH4) and nitrous oxide (N2O) are main GHG emitted from livestock production. In the estimation based on dry matter intake, total emission from enteric fermentation is 0.375 million tons annually in Japan. Animal effluent which is another source of methane from animals corresponds to 22.7% of total amount of methane emission. Total emission of N2O–N from animal effluent in Japan was estimated to be 8.7867Gg year 1. According to the IPCC report (1995), the total N2O–N emission is estimated 1500Gg year 1 in the world. Thus, N2O emission from Japanese animal agriculture accounts 0.59% in the global emission. As 0.717 Tg nitrogen year 1 have been excreted from the livestock in Japan, the excretion accounts 0.71% in 101 Tg year 1 of total nitrogen excretion from the livestock. Relatively lower nitrogen excretion as N2O can be calculated in Japan. D 2006 Elsevier B.V. All rights reserved. Keywords: Greenhouse gas; Methane; Nitrous oxide; Ruminant; Biogas; Kyoto protocol
1. Introduction The gases which bring greenhouse effect are water vapor and trace gases in atmosphere, a carbon dioxide (CO2) methane, chlorofluorocarbon (CFC-11,12) and nitrous oxide. The problem as greenhouse gases is an increase in the trace gases in the atmosphere such as CO2. The total emission of greenhouse gases including methane in 1997 was 8.5% higher than the level in 1990. In the 3rd session of the Conference of Parties to the United Nations Framework Convention on Climate Changes held in Kyoto December 1997, Japan owed the obligation to decrease by 6% of the total greenhouse gases emission in 1990 until 2008 to 2012 (Kyoto Protocol, 1997). Japan concluded the Kyoto Protocol on June 4, 2002. As of February 2, 2005, 140 countries and EU have concluded it now. The coming into effect requirement was filled by the conclusion of Russia, and the Kyoto Protocol effectuated on February 16, 2005. The
* Tel./fax: +81 155 49 5421. E-mail address: [email protected]. 0531-5131/ D 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2006.02.043
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J. Takahashi / International Congress Series 1293 (2006) 13–20
reduction of greenhouse gas emission is a global issue. CO2 occupies about the half of the entire greenhouse effect, and CH4 is greenhouse gas succeeded to CO2 [1]. The concentration of atmospheric CH4 is only 2 ppmv or less and slighter than 350 ppmv of carbon dioxide. An increase in CO2 is largely originating in the combustion of the fossil fuel according to the development of the ore industry in advanced nations after the Industrial Revolution. As CH4 is removed reacting with radical OH of the troposphere, the longevity of CH4 (12–17 years) in atmosphere is shorter than 50–200 years of CO2 [2]. The concentration of atmospheric methane at present is twice of the value before the Industrial Revolution. The annual rise of the concentration has shown a rapid increase of 1.0–1.3% in the last decade compared with 0.5% of CO2. However, the absorptivity of infrared rays is already near saturated because a large amount of CO2 exists in atmosphere and only absorption increases around a big absorption zone at 16Am wavelength. Even if the concentration increases, the absorption ability of infrared ray in CO2 does not change so much. As for CH4, the relative absorptivity of the farinfrared radiation is large (about 21 times CO2 for each molecule, and 58 times in the weight ratio) and absorptivity is not saturated like CO2. The absorptivity of the far-infrared radiation in methane rises proportionally to the temperature rise. Most of absorption zones of methane are in 8–13Am that do not overlapped the absorption zones of water vapor and CO2. Therefore, even a little increase of methane concentration in atmosphere exerts extremely strong effect on global warming. It is possible to divide the sources roughly into a natural source and an anthropogenic source though the source includes many things. The annual emission of CH4 in the atmosphere accounts for 535 Tg according to the report of IPCC (Intergovernmental Panel on Climate Change) in 1994 [3]. The 85Tg derived from the rumen fermentation of the ruminant animals. When the methane emission of 25 Tg from animal waste includes in the calculation, methane emission from ruminants occupies 20% of total emission. This is one of big sources as well as marsh (wetland) 115Tg. Sixty percent or more of the amount of methane production is directly attributed to human activities. The enlargement of rice paddy (60 Tg) and livestock is almost proportional to the expansion of human population. This may be the main cause of an increase in CH4 in atmosphere. CH4 produced by rumen fermentation of ruminant animals is emitted into atmosphere by eructation. On the other hand, the main anthropogenic sources of N2O are from agriculture and animal agriculture. Though there are some difficulties in the quantitative assessment of casual relation between nitrogen applied as fertilizers or composts and N2O emission, 0.01–2.0% of applied nitrogen is estimated to convert to N2O. The present paper deals with current situation of GHG emission from livestock production in Japan. 2. Methane emission of enteric fermentation of farm animals The ruminant species is a big group which contains wild kinds of the giraffe and deer families, etc. including bovine, and even only the Bos. sub-family is classified into five genera and 14 species. Target one for the control is milking cow and domesticating beef cattle. The amount of the CH4 emitted by eructation from lactating cow is presumed to be 200–400 l/day though 1,200,000,000 domestic cattles are raised on the earth. One or two drum cans equivalent of pure methane will be emitted into the atmosphere by milking one cow every day.
J. Takahashi / International Congress Series 1293 (2006) 13–20
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Fig. 1. Methane emission from rumen fermentation from ruminant farm animals. Live body weights of cattle and buffaloes were assumed to be 600 kg. Methane emission was estimated from 80 ml kg 0.75 body weight h 1.
Fig. 1 shows methane emission from rumen fermentation from cattle and buffalo calculated from animal numbers. The calculation is based on live body weights of cattle and buffaloes which were assumed 600 kg and methane emission was estimated from 80 ml kg 0.75 body weight h 1. Fig. 2 shows the methane emission from small ruminants. The calculation is based on live body weights of sheep and goats which were assumed 50kg and methane emission were estimated from 65 ml kg 0.75 body weight h 1. Table 1 shows estimated methane emission from enteric fermentation of farm animals in Japan based on DMI. Total emission from enteric fermentation is 0.375 million tons annually. 100 drum cans of 100% CH4 will be emitted there into an atmosphere everyday if dairy farmer keeps 100 lactating cow in his farm. Although CH4 is combustible, there is no example of happening of the explosion accident because about 100 times are diluted with the expiration. In other words, it should be impossible to recycle CH4 emitted through eructation as a combustible energy resource, and control the quantity of production in the rumen from the viewpoint of the prevention of global warming. The mechanism of methane production in the rumen and its biological significance are discussed as follows. Ruminant animals such as cattle, sheep and goat have reticulo-rumen that produce good quality proteins of milk and meat, and offer human from the low-quality
Fig. 2. Methane emission from rumen fermentation from small rumen. Live body weights of sheep and goats were assumed to be 50 kg. Methane emission was estimated from 65 ml kg 0.75 body weight h 1.
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J. Takahashi / International Congress Series 1293 (2006) 13–20
Table 1 Estimated methane emission from enteric fermentation of livestock in Japan based on DMI Animals Dairy cow Lactating Dry Replacing Beef cattle Reproducing Fattening JB(N1 year) (b1 year) HF Sheep and goat Pig Horse Total
DMI (kg)
CH4 production (l day 1 head 1)
15.8 7.5 7.9
446.5 255.4 267.3
5.8
201.9
7.3 5.2 9.5 0.8 4.2
249.3 181.8 312.2 15.9 69.0
No. of animals
CH4 emission (Tg year 1)
1,904,875 1,082,000 332,230 490,575 2,292,700 696,450
0.182 0.126 0.022 0.034 0.150 0.037
565,000 226,550 804,750 66,000 11,335,000 24,000 15,623,675
0.037 0.011 0.066 b0.001 0.012 b0.001 0.345
Source: Shibata [4].
biomass resources like grasses which cannot be used directly as human foods. Carbohydrate in roughage such as grasses is cell wall constituent, cellulose and hemicellulose. These structural carbohydrates cannot be decomposed by animal’s digestive enzymes (Photo 1). Reticulo-rumen means rumen and reticulum which take part in rumination. These dietary fibers efficiently receive various bacterial digestion with the enzymes secreted from cellulolytic bacterial cells in the huge capacity (200 l) of rumen (Fig. 3). Then the decomposed mono-saccharide receives the fermentation action in the bacterial cells. The fermentation product is volatile fatty acids such as acetic acid. These VFAs are energy sources or substrates of body fat and bacteria and protozoa which proliferate by these fermentation processes and are used for the host animals to maintain and to produce as microbial protein. This digestion and the fermentation process by this microorganism is indeed a clever device.
Photo 1. Scanning electron microscopy of bacterial digestion of fibrous fraction in the rumen.
J. Takahashi / International Congress Series 1293 (2006) 13–20
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Fig. 3. Bacterial digestion and fermentation of feed fibers in the rumen.
Besides the digestion of fibers, essential amino acids, vitamin B group and K are synthesized under usual feeding condition. This microbial metabolism does a large contribution to human nutrition through animal nutrition. However, H2 and CO2 are produced when fibers are digested and fermented by the rumen bacteria. Consequently, a huge amount of CH4 is produced with methanogenic archaea in the rumen expressed by the simple reaction: 4H2+CO2YCH4+2H2O. However, this methanogenic pathway by CO2 reduction is a complex system, and seven steps of enzymic reactions involve in the reduction. As H2 obstructs the proliferation of useful bacteria in the rumen, methanogenic archaea has the role as a scavenger of this H2 in the rumen, and is useful for the homeostasis of the rumen ecosystem. In general, the amount of CH4 produced is large in feed and high in fiber content. However, the main substrate of the methane is digestible structure carbohydrates (cell wall constituents) such as hemicellulose. Therefore, it is demonstrated in sarcasm that forages rich in digestible fibers to make a performance of ruminant animals result in large emission of methane. It is the most difficult point for this contradiction to think about the control of the methane generation in the rumen. CH4 is a combustible gas with the calorie of 892.6 kJ (25 8C, 1013hPa) per mole and loss of the feed energy is estimated 7–10%. Recently, attention is paid to the CH4 emission problem from ruminant animals by the point of environmental problems rather than an economical aspect of the energy metabolism. Methanogenic archaea is classified into 12 genera, and some kinds of important archaea have been isolated in the rumen. These methanogenic archaea are Gram-positive strict anaerobe. They are cocobacilli about 0.7Am wide and 1.8 Am in length and non-motile spheres with 1.5–2.0 Am in diameter which forms big clusters. Since 20% of rumen methanogenic archaea is parasitic on the surface of protozoan body (Photo 2). The decrease in the CH4 generation is clarified by defaunation (removal of protozoa). Excess feeding of concentrate mixture such as cereals exerts the influence on protozoa. In consequence, methanogenesis may decline. This is a reality in a modern high performance
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J. Takahashi / International Congress Series 1293 (2006) 13–20
Photo 2. Some species of methanogen associated with ciliate protozoa. 20% methanogen may be endosymbionic.
cow milking and beef cattle feeding. However, for consolidated milk cow at the present age which pursues high-ranking production and meat, a negative side of frequent incidence of metabolic diseases such as lactic acid acidosis and the displaced abomasum etc. has come to light. Moreover, the adverse effect of H2 is not removed in this case. As for the removal of H2 by a strong reduction reaction, the effect is highest in the CO2 reduction obstruction. Ruminal reduction of nitrate contained in the forage plants shows a remarkable effect of control in the ruminal CH4 generation. When the nitrate intake is too large, the subclinical poisoning of nitrate is takes place. Moreover, approval ionophores such as monensin, salinomycin are known as propionate enhancers the propionic acid by the antibiotic which has been put to practical use, and the suppressing effect of these antibiotics to on rumen methanogenesis. However, there are some anxieties due to appearance of a resistant bacteria by the long-term use, remaining in the products, and shifted anxiety to the human body. Additionally, though the control effect on rumen methanogenesis is reported as for the halogen compounds or saturated and unsaturated fatty acids, there are some adverse effects on the fiber digestion problem as the chronic poisoning. Therefore, practical use of these compounds is not shown. In other words, to control only the rumen CH4 production without adverse effect on the useful bacteria in the rumen and the manipulation method must be safe for animal and human bodies and environment. In Japan, the effects of various probiotics, the plant extracts and a sulfur containing amino acid are being examined as feed additives of a natural material which suits these conditions now [5]. On the other hand, animal effluent which is another source of methane from animals corresponds to 22.7% of total amount of methane emission. This CH4 can be recycled as an energy resource by the anaerobic fermentation processing. Table 2 shows estimated methane emission (Gg year 1) from animal effluent in Japan. Rapid development of animal agriculture industry in Japan has resulted in a remarkable imbalance between the increased amount of animal effluents and cultivated land area to apply them. An absolute shortage of land area to produce animal feed and animal production highly dependent on imported ingredients of concentrates has amplified the imbalance. The research of the plant level has been advanced in the Europe dairy farming countries such as Denmark and Germany, and the CH4 energy from the domestic animal
J. Takahashi / International Congress Series 1293 (2006) 13–20
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Table 2 Estimated methane emission (Gg year 1) from animal effluent in Japan Dairy cow Manure Drying Biogas Composting Combustion Urine Biogas Sludge process Accumulation Slurry Drying Biogas Composting Accumulation Total
Beef cattle
Pig
Laying hen
Broiler
Total
0.0065 0.0415 5.3526 0.0160
0.0040 0.0061 0.6316 0.0044
0.0075 0.1335 0.8415 0.0240
0.0439 0.1228 0.8877 0.0920
0.0093 0.0825 1.0956 0.2560
0.0676 0.3864 8.8090 0.3924
0.0001 0.0000 0.1417
– – 0.0082
0.0008 0.0000 0.1104
– – –
– – –
0.0009 0.0000 0.2603
0.00730 0.06200 0.57090 6.94600 13.14460
0.0125 0.1613 7.1577 0.1656 8.1478
0.0029 0.0275 0.2508 0.8096 2.2085
– – – – 1.1464
– – – – 1.4434
0.0227 0.2508 0.0000 7.9212 26.0907
Source: Haga [6].
excreta has already been made the capital at the stage of practical use. In Japan these researches have just started. Animal effluent cause not only the stink problem but also the eutrophic pollution problem of the lake, pond, river and the sea water by nitrate nitrogen which derives from ammonia nitrogen. In addition, because nitrous oxide (N2O) which is derived from ammonia becomes another greenhouse gas, and becomes the cause of acid rain, too, animal effluent processing is a world issue. Some EU countries have legislation to maintain a severe restriction method for animal effluent processing. That is, the control of the CH4 emission from animal is a big problem which includes the control of the CH4 Table 3 Estimated nitrous oxide emission (N2O–N Gg year 1) from animal effluent in Japan Manure Drying Biogas Composting Combustion Urine Biogas Sludge process Accumulation Slurry Drying Biogas Composting Sludge process Accumulation Total Source: Haga [6].
Dairy cow
Beef cattle
Pig
Laying hen
Broiler
Total
0.0064 0.0390 0.3825 0.0001
0.0004 0.0050 0.0392 0.0000
0.0156 0.2603 0.1245 0.0004
0.1920 0.5040 0.2760 0.0032
0.0672 0.0428 0.5618 0.0146
0.2816 0.8511 1.3840 0.0183
0.0038 0.1080 0.2445
0.0027 0.0096 0.0267
0.0375 2.7600 0.1725
– – –
– – –
0.0440 2.8776 0.4437
0.0116 0.0930 0.0653 0.0240 0.28350 1.26170
0.0172 0.2093 0.7050 0.0000 0.0060 1.0211
0.0112 0.0998 0.0690 1.2120 0.0795 4.8423
– – – – – 0.9752
– – – – – 0.6864
0.0400 0.4021 0.8393 1.2360 0.3690 8.7867
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fermentation in the rumen, the promotion of anaerobic fermentation of effluents to capture methane and use of the residue after fermentation as a fertilizer. Furthermore, an efficient conversion of methane energy remains to be elucidated for recycling. Not only the animal husbandry of one country but also all over the world correspondence is urged to contribute to the global warming prevention by the solution of these problems. 3. Nitrous oxide emission from animal effluent Table 3 shows estimated nitrous oxide (nitrogen basis) emission (Gg year 1) from animal effluent in Japan. Total emission of N2O–N from animal effluent in Japan was estimated to be 8.7867 Gg year 1. According to the IPCC report (1995) [7], total N2O–N emission is estimated 1500Gg year 1 in the world. Thus, N2O emission from Japanese animal agriculture accounts 0.59% in the global emission. As 0.717Tg nitrogen year 1 has been excreted from livestock in Japan, the excretion accounts 0.71% in 101Tg year 1of total nitrogen excretion from livestock. Relatively lower nitrogen excretion as N2O can be calculated in Japan. In Japan, however, excess amount of the untreated effluent resulted in contamination of high nitrate in underground water and pathogens such as cryptosporidium in surface water. The complaints to the pollution problems in animal agriculture industry have been increased as the drastic expansion of animal population in limited areas. The issues which should be resolved are the developments of various technologies for animal effluent management to control offensive odors and wastewater, and feeding management to reduce the excretion of nitrogen and phosphorus. For the exploitation of energy through anaerobic fermentation of animal manures and organic wastes, biogas plant is spreading gradually in animal industries in Japan. Many research projects have been carried out to withdraw the energy of methane in the process related to animal and organic effluent management. The fuel cell which uses animal effluents and organic wastes became actual ones depending upon the advancement of desulfurization technology such as biodesulfurization. Promoting the environmentally conscious agriculture which does not rely on the chemical fertilizer can be realized by solving issues on excess nitrogen problem and creation of recycled energy from animal effluent and organic wastes in animal agriculture. References [1] F. Peace, Methane: the hidden greenhouse gas, New Scientist 122 (1663) (1989) 37 – 41. [2] A.R. Moss, Methane, 1993, Chalcombe Publications, Kingston, pp. 23 – 47. [3] Intergovernmental Panel on Climate Change (IPCC), in: J.H. Houghton, L.G. Meria Filho, J. Bruce, Hoesung Lee, B.A. Callander, H. Haites, N. Harris, K. Maskell (Eds.), Climate Change 1994, Cambridge University Press, NewYork, 1994, pp. 25 – 27. [4] M. Shibata, et al., Estimation of methane production in ruminants, Anim. Sci. Technol. (Jpn) 64 (1993) 790 – 796. [5] J. Takahashi, et al., Modification of methane emission in sheep by cysteine and a microbial preparation, Sci. Total Environ. 204 (1997) 117 – 123. [6] K. Haga, Control of greenhouse gases emission (Jpn.), in: Reports on the Working Group for the Technology of Greenhouse Gases Control in Animal Husbandry, vol. 3, 1998, pp. 72 – 97. [7] Intergovernmental Panel on Climate Change (IPCC), Climate Change 1995: Impacts, adaptations and mitigation of climate change: scientific–technical analyses, in: R.T. Watson, M.C. Zinyowera, R.H. Moss (Eds.), Contribution of Working Group II to the Second Assessment of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambrige, 1995, pp. 747 – 771. Available from Cambridge.