In the paper there are described mathematical principles of biological, technological and economic model relations and connections in animal breeding on which the mathematical model AGRO-ZV is based. With the model it is possible to simulate impacts of the agricultural policy on livestock breeding economics and commodity economics in dependence on different agricultural policy variants. In the article there is illustrated a usage of the model for simulation of dairy cattle economics before (2003) and after (2004) the accession of the Czech Republic to the EU.