MOLDAVI: A model to predict environmental and economic performances of broiler farming systems

Modelling is a relevant tool to study both environmental and economical performances oflivestock systems. The aim of this paper is to present MOLDAVI, a model of broiler farmingsystems management under animal performances, environmental and economical issues. Thesystem is a combination of four sub-models representing the animals, the poultry house, themanure and the outdoor run for free-range systems. Animal performances (growth, feed intake, mortality) are simulated in relation with birds’ characteristics (growth rate), feeding (nutrient composition) and rearing environment (temperature, animal density). Concerning environmental issues, the model predicts NH3, N2O and CH4 emissions from manure and outdoor droppings as well as abiotic CO2 emissions from fossil fuel use (e.g. propane for heating). Manure characteristics are estimated using a mass balance approach between animal excretion and gaseous losses. Energy and water use from the system are also estimated. Economicalperformances are calculated from bio-technical results (animal performances, energy and water use) simulated by the model and economical references (€ per kg of live weight produced, price of feed) given as model inputs. In order to improve broiler farming systems performances, MOLDAVI has been developped to be sensitive to a large panel of farming practices including flock management (animal density, feeding strategies…), housing characteristics (type of ventilation, outdoor access…) and manure management (manure type…). Simulations could help understanding complexity in broiler farming systems and stress synergical or compensation effects. As an example, the decrease of feed nitrogen content could lead to a decrease in nitrogen excretion and gaseous losses, but it could aleviate growth performances and therefore economical profit. Moreover, to take into account indirect environmental impacts associated to feed production, MOLDAVI outputs could be used in combination with Life Cycle Assessment.