Water productivity of milk produced in three different dairy production systems in Southern Brazil

Water is a crucial resource to produce dairy milk and studies are required to identify opportunities for improvements in water management. This study evaluates the water productivity of milk (WPMilk) produced on 67 farms located in southern Brazil and the influence of dairy cattle production systems (pasture-based, 57 farms; semi-confined, 7 farms; confinement, 3 farms) on water productivity. Indirect and direct water flows were taken into account and the dairy milk was the output. Pasture yield was estimated based on a weighted average. Indirect water represented >98 % of water consumption for milk production on farms assessed. In the pasture-based system, the WPMilk ranged from 0.27 to 1.46 kg FPCM (Fat Protein Corrected Milk) m^-3 of water; in the semi-confined system it ranged from 0.59 to 1.1 kg FPCM m^-3; in the confined system, it ranged from 0.89 to 1.09 kg FPCM m^-3. Results show that 20 farms in the pasture-based system presented higher WPMilk than the maximum WPMilk of farms in the semi-confined system. Comparing outcomes of farms in the confined system with pasture-based system, similar results were observed with higher WPMilk on 22 farms in the pasture-based system. Results indicate that, regardless of the type of production system, water productivity is influenced by the dairy productivity indicators of the farm, such as milk yield and feed components. The large variability in the WPMilk was expected and reflects the inherent attributes and conditions affecting this indicator, which underlines the importance of assessing it on a farm scale. Consequently, achieving high dairy productivity indicators should be encouraged in the pasture-based system due to the environmental, economic and social advantages for the farmer. Results advance the knowledge about water flows and WPMilk in different dairy cattle production systems besides defining the first benchmarks for WPMilk produced on farms in Brazil.