This paper develops a demand-augmented positive mathematical programming model to analyze the relationship between environmental pollution from animal manure, manure policies and different pork production systems in the Netherlands. The model features substitution of conventional and alternative pork from the demand side and endogenous manure prices. It is found that policies that put restrictions on environmental pollution from manure decreases the conventional pork production systems, but increases organic pork production systems. The latter is considered an improved system from both an animal welfare and environmental point of view.