Methane emissions from reindeer - do reindeer fed lichens emit less methane than reindeer on a pelleted feed diet?

Abstract

Microbial fermentation in the world domesticated ruminant populations is thought to be responsible for as much as 13.5-33% of the global anthropogenic methane (CH4) emissions (World Resources Institute 2005, EPA 2004, Bodas et al., 2012). However, methane also represents a loss of 2-15% of the gross energy intake in these animals (Blaxter and Clapperton 1965, Holter and Young 1992, Johnson and Ward 1996). The objective of this current project was to study the effect on methane emissions from female reindeer (Rangifer tarandus tarandus) fed a mixed lichen diet (dominated by Cladonia stellaris) compared to a grass based commercially available pelleted feed (RF from Felleskjøpet, Norway). The pellets contained high concentrations of protein (12.7% of dry matter (DM)) and water-soluble carbohydrates (5.9% of DM) compared to lichens (< 2.6 and 0.1% of DM respectively), while the lichen diet contained as much as 78.7% of DM hemicellulose. Total methane emissions were recorded during 23 hours, twice per animal on the two different diets, using an open-circuit respiration chamber. Feed (~0.440 kg DM) was presented to the animal two hours after initiating the recording in the chamber. The reindeer (n=5) emitted 11.1 ± 1.0 g CH4 / animal / day when fed pellets, while their mean average methane emission was significant lower (P = 0.0009) when fed the lichen diet (7.3 ± 1.6 g CH4 / animal / day), given the same amount of DM. The amount of gross energy intake lost in the form of methane from reindeer on a restricted diet was 7.6 ± 1.0% fed pellets and 5.1± 1.6% feeding a lichen diet (P = 0.0002). This study suggests that intake of lichens depress methane emissions in reindeer. The implications of these findings are discussed, and data on methane emissions from reindeer compared to those reported in other ruminants.