Mogelijkheden van additieven om de methaanemissie in runderen te verlagen

A desk study was performed on the efficacy and applicability of feed additives to reduce enteric methane emission. This involves products that are fed in such low quantities and do not contribute in any other way to dietary nutritional value. A distinction is made between additives that at as a sink for hydrogen, and additives that have a direct inhibitory effect on methanogens. Both classes of additives appear to have a persistent effect and strong reducing effect on methane emissions up to more than 30%. For additives with a mode of action based on a shift in microbial activity and rumen fermentation profile (mostly products of plant origin) the results are far less consistent and the effects appear to be at least less persistent. Relatively less thorough research has been conducted with the latter class of additives. Moreover, the research mainly concerns the testing of plant extracts in concentrated form, with research on the plant itself as a herb containing thee bioactive compounds is lacking. Apart from their efficacy and expectations on persistency, for some additives there are additional concerns with respect o applicability and possible trade-offs towards animal and environment. This involves additives of plant origin as well as synthetic additives. In general, there is little information on the impact of diet and production conditions on persistency and efficacy of the methane reducing effects. The substantiation in this area of research is weak. Also, there is no information available on the interactions with a combined application of additives with a different mode of action, or on the efficacy with an alternating application of additives for which the rumen environment easily adapts. An important aspect that needs to be weighed with a successful application of additives in farming practice is the way the additives is introduced into the diet, and what are the consequences for dynamics of the effective concentration of the additives in the rumen environment throughout the day. Also in this area thorough research is essentially lacking. Finally, control has to be exerted by the farmer in how additives are introduced in the feeding management in order to guarantee efficacies observed in experimental research also occur under practical conditions, and to be able to account for these effects on emissions in the KringLoopWijzer (a farm assessment tool) and the national inventory of emissions.