genetic potential, adaptive capacity, etc.), although differences in reproductive rates, health and mortality and overall herd and farm management may also contribute. Besides, handling of animal wastes and its use for crop and feed production may be less sophisticated in developing than in developed regions, resulting in higher nutrient losses and GHG emissions.

Diet additives – pros and cons

Hundreds of peer-reviewed publications on feeding strategies to mitigate CH4 emissions from enteric fermentation in ruminant production have been published during the last decades, including several extensive review papers (Hristov et al., 2013). Diet additives such as plant secondary compounds (e.g. tannins, ethereal oils), electron receptors (e.g. fumarate), ionophores (e.g. monensin) or dietary lipids with high proportions of unsaturated fatty acids were frequently shown to reduce enteric CH4 production. However, effects, if expressed in CH4 per unit of digestible feed intake, are relatively small, and doubts exist whether they persist in the long term and are transferable to on farm and different production situations (Knapp et al., 2014).