The role ensiled forage has on methane production in the rumen

Methane emitted by ruminants is not only a significant greenhouse gas but a loss in productivity because of the energy lost from the animal. Ensiled forage is fundamental in the nutrition of housed ruminants. Therefore a review of how ensiled forages influences enteric methane provides an understanding of what mitigation measure are achievable by the producer and what further research is required. Inclusion of forage maize silage in diets has consistently shown 10-20% reductions in enteric methane reductions by numerous studies, however the level of reduction is dependent on the maturity of the forage the forage maize silage is replacing. Whereas inclusion of legume silages has been shown to have no significant benefits, even though this forage type has less structural carbohydrates than that of the grass silage it has substituted. Grass swards cut at their immature stage have been shown to reduce enteric methane but best practise of ensiling, silage fermentation and feed out is essential for this benefit to be fulfilled. Inoculants using Lactobcillus sp. can assist in doing this and in doing so greater prominance of this mitigation strategy can be given. Going forward the review picks up on further research in areas such as the type of Lactobaciilli sp. used as an innoculent as it may enhnce the rumen fermentation process itself; the use of exogenous fibrolytic enzmes in enhncing the ensiled forage digestability and tannin and saponin rich forages. These strategies have been inconsistent in delivering results or are uneconomically viable. However if research can be directed towards understanding how different methanogenic Archae operate in the rumen and targetted plant breeding of forages containing bioactive componds, then it may be possible to unlock the potential of future enteric methane mitigation approaches.