The role and management of whole-crop forage for organic ruminants

Summary

There is a large base of evidence that fermented whole crop forages can be grown and conserved successfully in temperate conditions such as the UK offers. As preservatives are generally eschewed in organic production the crop is generally cut earlier in line with recommendations for fermented whole crop forages. Starch and protein levels will be lower at earlier harvest dates. This results in penalties in yield, greater losses in dry matter during fermentation and can lead to secondary fermentation when the clamp is opened to feed. Most of the research work reviewed is based on cereal whole-crop, although there is a developing body of knowledge based on intercropping of cereals and legumes as well as crops such as kale. Much of this work is addressed at the needs of the low-input and organic producer where fertiliser inputs and purchased feeds (in particular) proteins to the farm system are minimised. The bulk of this research however, has focused on production and conservation and relatively little on feeding of the forages to livestock. This is especially the case for cereal/legume mixtures which are most interesting to the organic livestock producer. This is surprising as all production of whole crop forages either as sole crops or as mixtures are ultimately as feeds for livestock. The nutritional quality (especially protein) can be somewhat lacking when grown as a sole cereal crop and the inclusion of a legume has been seen to partially overcome this although due to lower dry matter yields can detract from the objective of preventing forage production penalties where these crops are grown as nurse crops for grass re-seeds. Most workers agree that dry matter intakes are stimulated when offered as a feed to ruminants but few workers have found an increase in animal performance (weight gains, carcase quality or milk yields). There are however definitely opportunities to reduce reliance on purchased concentrates by growing and including, in particular legume-based forage mixtures to organic livestock. This attribute has become more important recently in the UK due to limited sources and costs of organic protein sources to purchase. On farm where re-seeding of pastures is practiced, whole crop forages can provide an excellent nurse crop and alternative feed to grass silage and help to overcome the seasonal production penalty usually associated with grass re-seeds.