Excerpts from the report Introduction: This report describes a simulation model of a dairy herd. The description includes flow chart and computer source language representations of the model, together with explanatory text. Although the model is capable of producing information on many aspects of the dairy farm business, the immediate focus is on the selection of a policy for making herd replacements. The operation of the model requires information describing the situation to be analyzed. Other values are "built into" the model. Running the simulation relates the descriptive information and factual concepts in a logical pattern. The output consists of information on the prospective performance of the dairy herd in the situation specified.