Sheep Production Adapting to Climate Change by Veerasamy Sejian Raghavendra Bhatta John Gaughan Pradeep Kumar Malik S. M. K. Naqvi & Rattan Lal

Author:Veerasamy Sejian, Raghavendra Bhatta, John Gaughan, Pradeep Kumar Malik, S. M. K. Naqvi & Rattan Lal
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

10.2 Methane and Global Warming

CH4 is a potent greenhouse gas (GHG) responsible for global warming and is emitted from natural sources like wetlands and from anthropogenic activities such as leakage from natural gas systems and from the raising of livestock. Global warming potential (GWP) of CH4 is estimated to be 56 for over 20 years. It is a relative measure of how much heat a GHG traps in the atmosphere and compares the amount of heat trapped by a certain mass of the gas in question to the amount of heat trapped by a similar mass of CO2 (IPCC 2013). It is calculated over a specific time interval, commonly 10, 20 or 500 years, and expressed as a factor of CO2 (GWP of CO2 is 1). Natural processes in soil and chemical reactions in the atmosphere help to remove CH4 from the atmosphere. CH4’s lifetime in the atmosphere is much shorter than CO2, but CH4 is more efficient at trapping radiation than CO2.

CH4 emission attributed to livestock mostly occurs due to enteric fermentation and from manure management. CH4 emissions from livestock are estimated at about 2.2 billion tonnes of CO2 equivalent, accounting for about 80% of agricultural CH4 and 35% of the total anthropogenic CH4 emissions. CH4 emitted from livestock depends on the feeding system on which livestock are reared (Soren et al. 2015). Among the diverse factors associated with enteric CH4 production in ruminants, nutrition plays an important role. CH4 production will be lowered only if the feed that is offered to the animal is tailored to the metabolic requirements, with better digestibility, and significant portion of the nutrients are diverted towards production and less towards wastage and CH4 emissions (Grainger and Beauchemin 2011). For instance, in concentrate-based feeding system, a high-grain diet will result in less CH4 per unit of intake in ruminants, but feeding system solely on concentrate will have other implications. On the other hand, in pasture-based animal feeding systems in countries with a large agricultural sector (Argentina and New Zealand), the contribution of livestock to GHG emissions is considerably greater (Leslie et al. 2008; O’Mara 2011).

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