Factors Affecting Mitigation of Methane Emission from Ruminants: Management Strategies

ECOLOGIA BALKANICA 2015, Vol. 7, Issue 1 June 2015 pp. 171-190 Synopsis Factors Affecting Mitigation of Methane Emission from Ruminants: Management Strategies Afshar Mirzaei-Aghsaghali1*, Naser Maheri-Sis1, Seyed Alireza Siadati1, Nader Jalilnejad2 1 - Department of Animal Science, Islamic Azad University, Shabestar Branch, Shabestar, IRAN 2 - Department of Agriculture and Natural Resources, Mahabad Branch, Islamic Azad University, Mahabad, IRAN *Corresponding author: Abstract. Nowadays, greenhouse gas emission which results in elevating global temperature is an important subject of worldwide ecological and environmental concern. Among greenhouse gases, methane is considered a potent greenhouse gas with 21 times more global warming potential than carbon dioxide. Worldwide, ruminant livestock produce about 80 million metric tons of methane each year, accounting for about 28% of global emissions from human related activities. Therefore it is impelling animal scientists to finding solutions to mitigate methane emission from ruminants. It seems that solutions can be discussed in four topics including: nutrition (feeding), biotechnology, microbiology and management strategies. We have already published the first review article on feeding strategies. In the current review, management strategies such as emphasizing on animals type and individual variability, reducing livestock numbers, improving animal productivity and longevity as well as pasture management; that can be leads to decreasing methane production from ruminant animal production are discussed. Key words: global warming, methane, enteric fermentation, ruminant, management. Abbreviations: GHG - greenhouse gas; WSC - water soluble carbohydrate; MCR - methane conversion rate; F:C ratio - forage to concentrate ratio; CT - condensed tannins; DMI - dry matter intake; PEG - polyethylene glycol; VFA - volatile fatty acids; FA - fatty acid; bST - bovine somatotrophin; OSHF - Overseas Holstein; FCCC framework convention on climate change. Introduction Climate change is a subject of global environmental concern. Increased anthropogenic Greenhouse Gas (GHG) emissions have increased the global temperature the last 100 to 200 years (MIRZAEI-AGHSAGHALI & MAHERI-SIS, 2011). Methane is considered a potent greenhouse with capability of trapping 21 times more heat (Global Warming Potential) than carbon dioxide also its life time in the © Ecologia Balkanica http://eb.bio.uni-plovdiv.bg atmosphere is 9-15 years and over the last two centuries, methane atmospheric concentrations have more than doubled arising 1% yearly in comparison with 0.5% of carbon dioxide. Worldwide, ruminant livestock produce about 80 million metric tons of methane each year (representing 11% sheep and goat), accounting for about 28% of global emissions from human related activities (MURO-REYES et al., 2011; UMEGHALU & OKONKWO, 2012; SHRESTHA et Union of Scientists in Bulgaria – Plovdiv University of Plovdiv Publishing House Factors Affecting Mitigation of Methane Emission from Ruminants: Management Strategies al., 2013). Under the Climate Change, the UK Government is legally required to reduce greenhouse gas (GHG) emissions across the UK economy by 80% of 1990 levels, by 2050. The agriculture sector is committed to playing its part in meeting this national goal and will need to demonstrate an 11% reduction on 2008 levels, by 2020. To support the industry’s position and efforts, better data are required on the carbon footprint of milk production from dairy farms. Focusing on more efficient use of inputs will also help reduce costs of production, as well as enhance the environmental credentials of the dairy industry (DAIRY CO, 2012). Ruminant animals (particularly cattle, buffalo, sheep, goat and camels) produce significant amount of methane under the anaerobic conditions of the digestive processes (SEJIAN et al., 2011a; ASSAN, 2014; ASSAN, 2015). Methane produced during anaerobic fermentation in the rumen represents 2-12% gross energy loss and emission from livestock contributes approximately 15% of the total atmospheric methane flux (ZHI-HUA et al., 2012; MAHESH et al., 2013). CH4 is considered a ‘greenhouse gas’ and emission of the global cattle population of 1-3 billion are estimated to be 58 million tonnes/year, or 73% of the emissions from all livestock species according to the US Environmental Protection Agency (1994) (TIEMANN et al., 2008; KURIHARA et al., 1999). As indicated before, dietary changes are a promising means to reduce CH4 losses. Such changes may well affect the composition of the products (WAGHORN & WOODWARD, 2004). With appropriate strategy and potential future technologies and management practices could reduce CH4 emissions per unit of animal product by 25–75% (MOSIER et al., 1998). However, except for the improved feeding management, the present technologies to control CH4 emission from ruminants are seen with pessimism (JOHNSON et al., 1996; SEJIAN et al., 2011b). Important manure management factors affecting CH4 formation during storage are the dry matter (DM) content of manure and its storage duration, and also the ambient temperature (STEINFELD et al., 2006; MIRZAEIAGHSAGHALI & MAHERI-SIS, 2008). This review looks more closely at the reasons for, and the consequences of, methane production from ruminant livestock which in turn is dependent on management strategies. To discuss factors relation to emissions of GHG’s (specific methane gas) from ruminants, we divided them in four groups, nutrition, management, biotechnology and microbiology. In this article, we will discuss factors relation management strategies and factors relation to biotechnology and microbiology will discuss in further article. 1. Animals - type and individual variability The decrease in emissions through low CH4 producing animals has been debated in the last few years. It has been established by several research groups that between-animal variability, at the same level of performance and using similar diets, is high. Methane production from individual animals may vary over time, even when animals are fed a constant amount of the same quality feed each day. Within animal variation in absolute CH4production from day-to-day in sheep and cattle has been reported to be approximately 7% (coefficient of variation, CV) when animals were fed a constant amount of consistent quality feed. One group of researchers reported that the CV for day-to-day variation in CH4 production was approximately 27% whether animals were fed ad libitum or on a restricted diet (JOHANNES, 2008, New Zealand, pers. comm.). Intensification of livestock production through better breeding and/or feeding to decrease global greenhouse gas emissions needs to be carefully assessed and will remain a hot debate in the foreseeable future (MARTIN et al., 2010). Calorimetric studies have reported between-animal differences (CV) in daily CH4 production of 7-8% and 11.7% when animals were fed a constant di (...truncated)