... allow the characterization of the poultry production (sub-) systems, the scale of breeding and the realisation of the cost- benefit analysis of the mass vaccination campaign against H5N1 in these ... production systems in place, including the occurrences of diseases and to evaluate the cost- benefit impact of the mass vaccination programme implemented at local level in Long An Province, in the ... 3.1. Typology of the poultry production systems The scale of poultry breeding and the type of poultry races are really diversified in each ecological zone of Long An Province. Investigation...