The project is part of the research programme ‘Low Emission Animal Feed’ and will contribute to the ambition of the dairy sector to reduce methane emission by dairy cows in the Netherlands by 30% in 2020.
In ruminant animals, methane is mainly produced during fermentation of feedstuffs in the rumen and to a lesser extent in the hindgut. Since methane is a greenhouse gas and a loss of dietary energy to the animal, research efforts have been made to investigate (nutritional) methane mitigation strategies. Increasing the proportion of concentrates in dairy cattle rations may result in a lower enteric methane production per kg of milk produced. However, decreasing the forage to concentrate ratio in ruminant diets counteracts the aim to use the lowest possible amount of human edible feed resources per unit of animal product. The latter is relevant because ruminants have the ability to convert fibrous feedstuffs that are inedible to humans into human-edible energy and protein. This feature may therefore increase their importance in terms of global food security, provided that the challenge of reducing greenhouse gas emissions, in particular methane emissions, can be successfully addressed. The use of feed additives to reduce methane emissions may be a suitable mitigation strategy, although, as a result of microbial adaptation in the rumen, some additives result only in short term methane reduction. Moreover, the effectiveness of an additive may also depend on the type of diet fed and physiological state of the animals. Another aspect that needs to be taken into account when selecting methane reducing feed additives, is scientific proof for their effectiveness in vivo. Additives that have been shown to reduce in vitro methane production will not necessarily show the same effects in vivo. Within this PhD project, the aim is to gain more information on the methane reducing potential of feed additives, which will be tested using the Wageningen respiration chambers.