Effect of cut number, maturity stage and conservation method on digestibility and mineral content of a grassclover mixture

During three consecutive years, samples of a grass-clover mixture from the first and third cut were collected at two stages of maturity (30 days apart) on the same experimental plot. After cutting, the forage samples were either frozen (-20ºC), artificially dried (forced air at 30ºC, <45% relative humidity), wilted on the field and subsequently barn dried, field dried, ensiled with a dry matter (DM) content of 30% or ensiled with a DM content of 50%. A total of 42 forage samples were analysed for in vivo digestibility using adult sheep and for mineral contents. Although digestibility varied slightly with the method of conservation, the most important factors affecting digestibility were cut number and stage of maturity. With the exception of calcium content, which was decreased by field drying, mineral contents were not affected by conservation method. These results emphasize the importance of a careful handling of the forage during harvesting and conservation. If the forage is accurately treated, losses in digestibility and mineral content due to conservation may be virtually prevented.