This study employs duality theory to model the dairy industry. Supply and demands for milk, cull cows, feed, labor and veterinary services were simultaneously estimated using Weighted Least Squares. Elasticities and partial adjustments were obtained for the Nation and the following regions, Appalachia, Cornbelt, Northeast, Pacific, Southern Plains and Upper-Midwest. Predictions for the change in quantity of goods demanded and supplied were made assuming a parallel shift in the supply of milk and demand for feed. In conclusion, predictions on the impact of bovine Somatotropin are made assuming all results are correct.