We present a method for modeling livestock production systems (MLPS), based on unified modeling language. A livestock production system is viewed as having four aspects: production, decision, action and resource. A three-stage process is used. First, the main interactions between the production system and external systems are modeled for each aspect by means of use case diagrams. Second, internal processes detail these use cases with refined use case, sequence or activity diagrams. Third, the model is built. Package and class diagrams model its structure, while sequence, activity, statechart and time diagrams represent its dynamics. We applied MPLS to a simplified beef production example.