2012 Jiva April Page 56-59

GENERAL ARTICLE

METHANE EMISSION FROM RUMINANTS ENVIRONMENTAL IMPLICATIONS AND STRATEGIES FOR REDUCTION.

J. Ind. Vet. Assoc., Kerala. 10 (1)

Lalu. K., Usha. A.P., Venkatachalapathy.R.T and Prasanth.V. Centre for Pig Production and Research, Mannuthy INTRODUCTION

of polar ice cap.

Methane, the simplest aliphatic hydrocarbon, is one of the gaseous end products of fermentative digestion in ruminants. It is released into the atmosphere by eructation. It is twenty times more potent than carbon dioxide as green house gas.

Its atmospheric concentration has doubled since industrial revolution. About 22 Percent of anthropogenic methane is from ruminants.

Continuous release of methane is a matter of worry. It also contributes to green house effect by the process called radiative forcing leading to global warming which in turn result in erratic weather patterns, desertification and rising of sea level due to melting

METHANE PRODUCTION BY INDIAN LIVESTOCK

ENVIRONMENTAL HAZARDS DUE TO METHANE Among the entire green house gases methane is one of the most dangerous as its radiative forcing effect is very high that the greenhouse

56

Indian livestock contribute about 14 Percent of total methane emitted by world livestock.

According to Khan et al., (1996) methane production per head of animal (cattle/buffalo) is only 170 liters/day which is much less than in the developed countries where animals are managed in factory style. Comparative emission of methane from animals is presented in Table 1. The energy content of methane is very high (13.25 Kcal/g) and the amount of methane belched by Indian cattle is equivalent to the feed costing to Rs 2.7 crores per day.

potential of one unit of methane is expressed as 7.5 C equivalent. Moreover the rate of production of methane is higher when compared to any other green house gases. Methane has both direct and indirect effect on climate. It interacts directly with chlorine in presence of infrared energy in the upper troposphere

GENERAL ARTICLE

and lower stratosphere leading to depletion of ozone layer. Indirectly it reacts with carbon dioxide a green house gas. The reaction is complex as 1) methane has absorption band in the infrared region 2) It is oxidized in troposphere by free hydroxyl radical 3) It is sizeable source of carbon monoxide through oxidation. 4) Stratospheric methane can react with chlorine from hydrochloric acid which destroys ozone layer.

METHANOGENESIS IN RUMINANTS Methane is produced in rumen strictly under anaerobic condition and serves as a hydrogen sink.

Most of the methane is produced in rumen by the reduction of carbon dioxide and some is derived from formate. Methanogenic bacteria are mainly responsible for methane production, which involves a specialized biochemical function.

Methanogenesis is a very intricate process that involves vitamin B12, folic acid, coenzyme (2 Mercapto ethane sulfonic acid), fatty acid and methyl butyrate. Half of the hydrogen produced during fermentation of carbohydrate is used for propionate production , biohydrogenation of unsaturated fatty acid and the other half for methane production The fermentation reaction are given below

1. C6 H12 O6

2CH3 COOH + 2CO2 + 8(H) (Acetate) (Methanogenic)

2. C6H12O6

2CH3 CH2 COOH + 2H2O + 4(H) (Propionate) (Glucogenic)

3. C6H12 O6

CH3 CH2-CH-COOH + 2CO2 + 4(H) (Butyrate) (Methanogenic)

Of the sixteen hydrogen molecules produced during the fermentation of carbohydrate, eight hydrogen molecules are utilized for propionate formation and other eight is converted to methane as shown.

4H2 + CO2

CH4 + 2H2O

Ruminants produce about 20g of methane for each kg of dry matter intake. Methane production in cattle is affected by variety of nutritional factors including level of intake, type of carbohydrate, forage processing, and change in the rumen microflora. Diet favoring propionate production in rumen causes decrease in methane and diet like roughage favours acetate production, which increases methane production. The molar proportion of volatile fatty acid plays a key role because fibrous feed results in higher methanogenic VFA (Preston and Leng 1987). So narrowing of the acetate: propionate ratio would increase performance in ruminants.

Substrates

Products

CO2, H2 and HCOOH

CH4, CO2 and H2O

Methanobacterium formicicum

HCOOH

CH4, CO2 and H2O

Methanobrevibacter ruminantium

HCOOH

CH4, CO2 and H2O

Methanobacterium mobile

HCOOH

CH4, CO2 and H2O

Methanosarcina barkerii

Methanol, Acetate

CH4, CO2 and NH4

Methanobacterium ruminantium

METHANE MITIGATION -A BOON TO FARMERS AND ENVIRONMENT It is desirable to maximally utilize fibre for ruminant production, because plant fibre is the most abundant organic matter that is available, and the greatest merit of ruminants is the ability to utilize

fibre. As the current practice of feeding highconcentrate diets to cattle is a luxury that future generations may not experience. An improvement in fibre utilization will become increasingly important.

Therefore, it is critical to develop strategies aimed at reducing ruminal methanogenesis without

JIVA Vol. 10

Bacteria

Issue 1 April 2012

Table.2. Methanogenic bacteria and their substrates for methane production

57

GENERAL ARTICLE

depressing fibre digestion.

Reduction in methane emission by ruminants may be one of the means to achieve animal productivity in environment friendly manner.

Reducing methane up to 70 Percent will be beneficial for reducing fodder wastage, increase in milk production, better fat percentage, and for better animal health.

METHODS OF METHANE MITIGATION There are different methods to reduce methane from ruminants which includes I. Proper managemental practices II. Manipulation of rumen ecosystem III. Using vaccine against methanogens I. PROPER MANAGEMENTAL PRACTICES a. Controlled grazing It is cheap and simple strategy to keep animals in smaller area to graze. Such controlled grazing decreases methane production and should formulate an ideal grazing schedule that minimize methane and maximize efficiency (USEPA, 1998). b. Selective breeding Studies in New Zealand have shown that there are significant differences in methane emission between individual sheep on same diet. This suggests that breeding for low methane out put may be a strategy for methane mitigation. But such selective breeding of ruminants for low methane output is still at preliminary stage.

J. Ind. Vet. Assoc., Kerala. 10 (1)

c. Animal health and sanitary measures Chronic disease in livestock is a persistent problem in developing countries. In disease condition like foot and mouth disease and tuberculosis, there is less feed efficiency and more methane production .So better health management reduces methane production. d. Improving digestibility of diet The use of chopped straw, treatment of cereal straw with alkali or ammonia increases the intake and digestibility and reduces methane

58

production per kg organic matter digested.

Supplementation of Urea molasses mineral block (UMMB) reduces the methane release by increased utilization of diet(Turnbull et. al., 2000).

II MANIPULATION OF RUMEN ECOSYSTEM here are many techniques to manipulate the rumen ecosystem. Feeding of antibiotics, methane analogues and using genetic engineering tools can control methanogenesis in rumen. a. Defaunation Defaunation is a term used for the elimination of protozoa from the rumen. Anaerobic protozoa lack mitochondria, but contain hydrogenosomes, in which hydrogen is produced when pyruvate is converted to acetyl Coenzyme A and carbon dioxide. Defaunation reduces methanogenesis in rumen to an extent of 20 to 50 percent depending upon diet composition (Kreuzer et. al., 1986). b. Suppression of ruminal methanogenesis by chemicals Over the years extensive attempts have been made to reduce ruminal methanogenesis, including the addition of chemicals such as halogen compounds and antibiotics. The polyether ionophores, such as monensin and lasalocid, have been considered to be the most useful modifiers of ruminal fermentation, because propionate redection is increased and hence reduction in methanogenesis.

A peptide ionophore, aibellin was found to reduce methanogenesis and augment propionate production in the rumen without decreasing protozoal numbers, the digestibility of neutral detergent fibre, or the production of total volatile fatty acids (Hino et al., 1993). Recently, it has been reported that as low as 4 nmol of mevastatin and lovastatin, inhibited in vitro growth and methane production of ruminal methanogenic bacteria. c. Suppression of Ruminal methanogenesis by fats It has long been known that methanogenesis is reduced by the addition of fats or long-chain fatty

GENERAL ARTICLE

Chlorinated methane analogues such as chloroform, carbon tetrachloride and methylene chloride inhibit methanogenesis in rumen.

Halogenated alkanes also block the function of corrinoid enzymes (Vitamin B12dependent enzymes) in methanogenesis. Bromoethane sulfonic acid (BES) is a potent inhibitor of methanogenesis and growth of M. ruminantium. Among the halogenated methane analogues bromochloromethane (BCM) seems to be the most potent. (Trei et al., 1970; Sawyer et al., 1971; Chalupa, 1984).

III

VACCINES

Recently scientists of CSIRO (Australia) developed vaccine against methanogens using pseudumurein layer of its cell wall. This vaccine suppress the growth of methanogens subsequently reduces methane production.

CONCLUSION Ruminants are evidently major source of methane emission and so methane abundance would continue to grow in the atmosphere with rise in animal number and production. Reduction of methane emission from ruminants can be achieved by several methods viz., supplementation of critical nutrient through concentrate or green fodder, feeding urea molasses mineral block, defaunation variation of roughage: concentrate ratio, ammoniation of cereal crop residues, feeding of halogenated methane, use of vaccines etc. If proper feeding strategy and managemental practices are followed,

REFERRENCES Chalupa, W. 1984. Manipulation of rumen fermentation.

In: Recent Advances in Animal Nutrition (edited by haresign, W., Cole, D.), London, UK, Butterworths, pp 143-160.

Czerkawski, J.W. 1986. Transfer of metabolic hydrogen in the rumen. In: An introduction to rumen studies.

Oxford, UK; Pergamon Press, pp. 173-188.

Hino, T., Saitoh, H., Miwa, T., Kanda, M. and Kumazawa, S. 1993. Effect of aibelin, a peptide antibiotic, on propionate production in the rumen of goats. J. Dairy Sci., 77: 3426-3431.

Khan, M.Y., Murari Lal, Biswas, J.C., Haque, N. and Girdhar, N. 1996. Methane production from Indian livestock. National Symposium. Prospects of livestock and poultry development in 21st Century.

CARI, Izatnagar, India, pp 41.

Kreuzer, M., Kirchgessner, J. and Muller, H.L. 1986.

Effect of defaunation on the loss of energy in weathers fed different quantities of cellulose and normal or steam-flaked maize starch. Anim. Feed Sci. Technol., 16: 233-241.

Leng, R.A. 1991. Improving ruminant production and reducing methane emission from ruminants by strategic supplementation. EPA, Washington, D.C. Preston, T.R. and Leng, R.A. 1987. Matching ruminant production system with available resources in the tropics and subtropics penumble books. Armidale Australia.

Sawyer, M.S., Hoover, W.H. and Sniffen, C.J. 1971.

Effects of methane inhibitor on growth and energy metabolism in sheep. J. Dairy Sci., 34: 1191-1199.

Trei, J.E., Singh, Y.K. and Scot, G.C. 1970. Effects of methane inhibition on rumen metabolism. J. Anim.

Sci., 31: 256.

Turnbull, G.W., Cripe, K. and Mishra, S. 2000. Effects of molasses urea supplementation of buffalo diet in Gujarat state. India on work production, butterfat, animal weight and methane loss. In: Proceedings of II International Methane Mitigation Conference, June 18-23; Novosibirsk, Russia.

USEPA 1998. Small steps make a difference: Improving your cow-calf business and the emission of the southeastern USEPA 430-K-98-001, 12P.

Issue 1 April 2012

d. Halogenated Methane Analogues

methane production from ruminants can be reduced.

It will improve the energy utilization /production performance of ruminants and protect the environment by reducing global warming.

JIVA Vol. 10

acids in the rumen, especially unsaturated fatty acids (UFAs) such as linoleic and linolenic (Czerkawski, 1986). UFAs have toxic effects on methanogens and the reduction in methanogenesis appears to be mostly a secondary effect on fermentation. Both in vivo and in vitro experiments have showed that addition of fats and oils containing UFAs depressed fibre digestion as cellulolytic bacteria are sensitive to UFAs. Addition of alpha-tocopherol and beta-carotene alleviates the toxic effect of UFAs, and improves fibre digestion.

59