title: Measurement and prediction of enteric methane emission.
abstract: The greenhouse gas (GHG) emissions from the agricultural sector account for about 25.5% of total global anthropogenic emission. While CO(2) receives the most attention as a factor relative to global warming, CH(4), N(2)O and chlorofluorocarbons (CFCs) also cause significant radiative forcing. With the relative global warming potential of 25 compared with CO(2), CH(4) is one of the most important GHGs. This article reviews the prediction models, estimation methodology and strategies for reducing enteric CH(4) emissions. Emission of CH(4) in ruminants differs among developed and developing countries, depending on factors like animal species, breed, pH of rumen fluid, ratio of acetate:propionate, methanogen population, composition of diet and amount of concentrate fed. Among the ruminant animals, cattle contribute the most towards the greenhouse effect through methane emission followed by sheep, goats and buffalos, respectively. The estimated CH(4) emission rate per cattle, buffaloe, sheep and goat in developed countries are 150.7, 137, 21.9 and 13.7 (g/animal/day) respectively. However, the estimated rates in developing countries are significantly lower at 95.9 and 13.7 (g/animal/day) per cattle and sheep, respectively. There exists a strong interest in developing new and improving the existing CH(4) prediction models to identify mitigation strategies for reducing the overall CH(4) emissions. A synthesis of the available literature suggests that the mechanistic models are superior to empirical models in accurately predicting the CH(4) emission from dairy farms. The latest development in prediction model is the integrated farm system model which is a process-based whole-farm simulation technique. Several techniques are used to quantify enteric CH(4) emissions starting from whole animal chambers to sulfur hexafluoride (SF6) tracer techniques. The latest technology developed to estimate CH(4) more accurately is the micrometeorological mass difference technique. Because the conditions under which animals are managed vary greatly by country, CH(4) emissions reduction strategies must be tailored to country-specific circumstances. Strategies that are cost effective, improve productivity, and have limited potential negative effects on livestock production hold a greater chance of being adopted by producers. It is also important to evaluate CH(4) mitigation strategies in terms of the total GHG budget and to consider the economics of various strategies. Although reductions in GHG emissions from livestock industries are seen as high priorities, strategies for reducing emissions should not reduce the economic viability of enterprises.
authors.affiliation: Adaptation Physiology Laboratory, Division of Physiology & Biochemistry, Central Sheep & Wool Research Insitute, Avikanagar, Via-Jaipur, Rajasthan, 304501, India. drsejian@gmail.com
authors.forename: Veerasamy
authors.initials: V
authors.lastname: Sejian
authors.forename: Rattan
authors.initials: R
authors.lastname: Lal
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lakritz
authors.forename: Thaddeus
authors.initials: T
authors.lastname: Ezeji
mesh_terms: D000822:Animal Husbandry / Q000191:economics / Q000379:methods*; D000818:Animals; D057232:Global Warming; D058751:Livestock / Q000502:physiology*; D008697:Methane / Q000032:analysis* / Q000378:metabolism; D008954:Models, Biological; D013459:Sulfur Hexafluoride / Q000032:analysis / Q000378:metabolism
chemical_list: D008697:Methane; D013459:Sulfur Hexafluoride
references.citation: J Anim Sci. 1999 Jun;77(6):1392-401
references.pmid: 10375217
references.citation: J Anim Sci. 1998 Feb;76(2):617-27
references.pmid: 9498373
references.citation: J Anim Sci. 2005 Jan;83(1):182-6
references.pmid: 15583058
references.citation: Science. 2010 May 7;328(5979):689-90
references.pmid: 20448167
references.citation: J Anim Sci. 2009 Mar;87(3):1048-57
references.pmid: 19028842
references.citation: Br J Nutr. 1985 Nov;54(3):763-75
references.pmid: 3870696
references.citation: J Dairy Sci. 2010 Mar;93(3):1266-82
references.pmid: 20172247
references.citation: Arch Anim Nutr. 2007 Feb;61(1):10-9
references.pmid: 17361944
references.citation: J Environ Qual. 2003 Jan-Feb;32(1):269-77
references.pmid: 12549566
references.citation: J Anim Sci. 2003 Dec;81(12):3141-50
references.pmid: 14677870
references.citation: J Nutr. 1992 Nov;122(11):2239-56
references.pmid: 1331382
references.citation: J Dairy Sci. 2007 Jul;90(7):3456-66
references.pmid: 17582129
references.citation: Chemosphere. 2003 Sep;52(9):1381-8
references.pmid: 12867167
references.citation: J Anim Sci. 1998 Aug;76(8):2190-6
references.pmid: 9734871
references.citation: J Anim Sci. 2006 Jun;84(6):1489-96
references.pmid: 16699105
references.citation: J Environ Qual. 2006 Jan 03;35(1):14-20
references.pmid: 16391273
references.citation: J Dairy Sci. 2005 Aug;88(8):2836-42
references.pmid: 16027198
references.citation: Res Vet Sci. 1999 Aug;67(1):65-71
references.pmid: 10425243
references.citation: J Anim Sci. 2005 Mar;83(3):653-61
references.pmid: 15705762
references.citation: J Environ Qual. 2009 Jul 23;38(5):1796-802
references.pmid: 19643744
references.citation: J Anim Sci. 2008 Feb;86(2):384-9
references.pmid: 18042816
references.citation: Environ Sci Technol. 1994 Feb 1;28(2):359-62
references.pmid: 22176184
references.citation: Br J Nutr. 1965;19(4):511-22
references.pmid: 5852118
references.citation: J Anim Sci. 1995 Jul;73(7):2141-5
references.pmid: 7592102
references.citation: J Anim Sci. 1995 Aug;73(8):2483-92
references.pmid: 8567486
references.citation: J Dairy Sci. 2006 Feb;89(2):761-71
references.pmid: 16428643
references.citation: J Anim Sci. 1996 Dec;74(12):3112-24
references.pmid: 8994925
references.citation: J Environ Qual. 2003 Sep-Oct;32(5):1591-602
references.pmid: 14535299
references.citation: J Anim Sci. 2001 Feb;79(2):515-24
references.pmid: 11219463
references.citation: J Anim Sci. 2008 Oct;86(10):2738-48
references.pmid: 18539822
references.citation: J Anim Sci. 2004 Nov;82(11):3346-56
references.pmid: 15542482
references.citation: J Anim Sci. 2008 Oct;86(10):2642-50
references.pmid: 18469051
references.citation: J Dairy Sci. 2006 Jul;89(7):2649-58
references.pmid: 16772584
references.citation: J Anim Sci. 2007 Jun;85(6):1479-86
references.pmid: 17296777
references.citation: J Dairy Sci. 2007 Jun;90(6):2580-95
references.pmid: 17517698
references.citation: Isotopes Environ Health Stud. 2001;37(4):257-379
references.pmid: 12723792
references.citation: J Dairy Sci. 2007 Jun;90(6):2755-66
references.pmid: 17517715
references.citation: Lancet. 2007 Oct 6;370(9594):1253-63
references.pmid: 17868818