Operational research study of forage conservation systems for cool, humid upland climates. Part 1: Description of model

An improved operational research model is described for studying the economics of forage conservation systems, particularly for cool, humid, upland climates. This covers the whole process, from growth of grass, through all the conservation operations, to evaluation of conserved forage for feeding ruminants. Sub-models simulate growth of grass, drying and rewetting of swaths in the field after cutting, mechanical field operations, crop losses in the field and in storage, and drying in a barn, in relation to historical weather data. Forage is evaluated using a standard dairy cow ration formulation procedure, adapted to take account of variations in intake with quality of forage. Conservation can be represented as field-dried hay, barn-dried hay, wilted silage and direct-cut silage.