In addition to altering the FA profile of ruminant products, incorporating oilseeds to diets of cattle has been shown to reduce enteric CH4 emissions, as reviewed by Beauchemin et al. (2008) and Martin et al. (2010). Ruminal digestion is accompanied by emissions of CH4, one of the main anthropogenic greenhouse gases (GHG). Livestock account for 35–40% of global anthropogenic CH4 with the majority arising from enteric fermentation in ruminants (Steinfeld et al., 2006). Farm based life cycle assessment indicates that enteric CH4 accounts for more than 60% of total GHG emissions from beef and dairy production (Beauchemin et al., 2009a). Thus there is increasing interest in developing strategies to reduce enteric CH4 emissions.