EVALUATION OF A STOCHASTIC DYNAMIC REPLACEMENT AND INSEMINATION MODELFOR DAIRY-CATTLE

An approach to evaluating results from a stochastic, dynamic model for insemination and replacement of dairy cattle was devised using sensit ivity and behavioral analyses. Sensitivity analysis was defined as the quantification of the various outputs resulting from uncertain price and production inputs. Behavioral analysis determined how outputs chan ged when model specifications were changed. The variation in outputs t hat were identified by sensitivity analysis was used as an objective m easure to assess variation caused by behavioral analysis scenarios. A contemporary model was modified, and a base run was defined using Flor ida values for input variables. The model specifications that were var ied were decision horizon, number of milk production levels, and numbe r of days open classes. Effects of including seasonality of milk produ ction, milk price, and conception rate were examined. The necessary de cision horizon was shorter than other works would suggest. Optimal pol icies were influenced greatly by the number of days open classes, but not by the number of milk production levels. Removal of seasonality of milk production and conception rate resulted in meaningful changes in seasonal patterns of all outputs measured. Our results suggest that m odel specifications could affect results and should be evaluated objec tively when models are being developed.