Abstract #406

# 406
Optimal dairy farm management subject to greenhouse gas emissions constraints.
Di Liang*1, Thomas F. Rutherford1, Victor E. Cabrera1, 1University of Wisconsin-Madison, Madison, WI.

Dairy farm feed allocation decisions seek to maximize farm profit. We present a nonlinear programming model that chooses a robust policies among a set of dairy farm management strategies. In the optimal policy, animal feed may be produced or purchased to meet nutrition and production demands of cow groups in the herd. Nutrition requirements are calculated according to the National Research Council equations, production level, cow group, and lactation number. Farm-produced feed quantity and quality (e.g., total DM, CP, NDF, NEL, RDP) are simulated with the Integrated Farm System Model using daily weather data. The quality of purchased feeds is established from published research. Based on these, milk sales, the farm-produced feed costs, purchased feed costs and the greenhouse gas emissions from manure and enteric fermentation are calculated. The optimal solution addresses the dual objective of maximizing profit (milk income over feed cost) while limiting greenhouse gas emissions. Farm characteristics (e.g., breed, production level, culling rate, reproductive performance, cropping strategy), feeding strategies (e.g., high or low forage, grazing, CP content, grouping strategy, seasonal diets which address heat stress), and manure management options (e.g., direct field application, lagoon, manure pile) provide detailed control of the dairy management strategies, which characterize an optimal policy. Consequently, the optimal solution provides a list of best feeding strategies and manure management practices according to farm-specific characteristics that maximize profit and minimize greenhouse gas emissions.

Key Words: profitability and environment, feed allocation, optimization modeling