Forage breeding and management to increase the beneficial XXXX content of ruminant products.

@entity844 @entity1718 @entity1474 @entity4721 @entity7461 @entity291
The declining consumption of ruminant products has been partly associated with their high proportion (but not necessarily content) of @entity1718 . Recent studies have focused on the less prominent fact that they are also important sources of beneficial @entity1718 , including n-3 @entity1718 and conjugated @entity4721 . @entity7461 (18 : 3n-3) is of particular interest because it also contributes to improved flavour of beef and lamb. Many recent studies showed large effects of special concentrates on levels of @entity1718 in milk and meat. However, the 'rumen protection' treatments, needed to ensure a worthwhile level of @entity844 in products, are expensive. Herbage lipids are the cheapest and safest source of these @entity1718 and so breeding to increase delivery of @entity1718 from plants into ruminant products is an important long-term strategy. Plant lipids usually contain high levels of @entity1474 , particularly 18 : 2n-6 and 18 : 3n-3 which are the precursors of beneficial @entity1718 . Whilst some plants are particularly rich in individual @entity1718 (e.g. 18 : 3n-3 in linseed), there are also useful levels in grass and clover (Trifolium Spp.). Levels of @entity1718 in forages in relation to species and varieties are considered, as well as management and conservation methods. Relationships between levels of @entity1718 and existing traits and genetic markers are identified. The effects of forage treatments on the @entity844 content of ruminant products are reviewed. The higher levels of @entity1474 in milk from @entity291 fed clover silages show that the level of @entity1718 in herbage is not the only factor affecting levels of @entity1718 in ruminant products. Further effort is needed to characterise susceptibility of @entity1474 to oxidative loss during field wilting and biohydrogenation losses in the rumen, and the relative importance of plant and microbial processes in these losses. The pathways of lipolysis and lipid oxidation are reviewed and other plant factors which offer potential to breed for reduced losses are considered.
