Assessing greenhouse gas emissions in Tunisian dairy cattle systems using the CLEANED tool

This study assessed greenhouse gas (GHG) emissions from different dairy farming systems in Tunisia using the CLEANED tool (Comprehensive Livestock Environmental Assessment for Improved Nutrition, a Secured Environment and Sustainable Development). A typology of 102 dairy farms across 17 governorates identified three main systems: (i) landless or rainfed farms with limited forage, (ii) mixed rainfed–irrigated farms with moderate intensification, and (iii) large irrigated farms with diversified feeding. Emissions per kilogram of milk ranged from 0.83 kg CO₂-eq in Cluster II to 0.91 kg CO2-eq in Cluster III (p<0.01). Emissions per kilogram of live weight gain ranged from 55.8 to 66.2 kg CO2-eq (p<0.001), while emissions per kilogram of protein varied from 24.1 to 26.7 kg CO2-eq (p=0.005). On a land basis, emissions ranged from 3.18 to 3.82 t CO2-eq/ha (p<0.001). Methane was the predominant gas, followed by nitrous oxide and carbon dioxide. Intensification increased emissions per hectare and per kilogram of live weight gain but did not necessarily increase emissions per kilogram of milk or protein. These results highlight the need for system specific mitigation strategies focusing on feeding efficiency and improved manure and soil management.