DAFOSYM: A Dairy Forage System Model for Evaluating Alternatives in Forage Conservation

Abstract The dairy forage system model, DAFOSYM, is a simulation model designed to evaluate technologies and management strategies on representative dairy farms. The model integrates crop growth, harvest, storage, feeding, animal utilization, and economic analysis. Corn and alfalfa growth are simulated using historical weather data. Alfalfa harvest includes mowing, field curing, raking, baling, and chopping; losses and quality changes are modeled as functions of the mechanical treatment, field curing time, and weather. Storage losses and quality changes are functions of the type of storage and the crop moisture content. Stored feeds are supplemented with soybean meal, distiller's grain, corn grain, and purchased hay to provide balanced diets for a given herd. Costs of crop production, machinery, storage facilities, labor, and purchased feeds are subtracted from the income of milk and excess feed sales to determine a measure of return. Simulation over many years of weather conditions is used to evaluate the long-term benefit and risk of a technology or strategy on a representative dairy farm. The model helps identify the best strategy for forage production and allocation to a dairy herd. The most appropriate type, size, and number of storage facilities, and the appropriately sized forage harvesting equipment are determined for a representative dairy farm.