Environmental impacts of cow’s milk in Northern Italy: Effects of farming performance

A Life Cycle Assessment was conducted on 55 dairy farms located in Northern Italy to investigate the effect of dairy farming performance on the environmental impact of milk production. Feeds used in diet formulation were analyzed for nutrients contents by near-infrared reflectance technique, and the real composition was used to estimate methane emissions from enteric fermentation and manure handling. The functional unit was 1 kg of fat and protein corrected milk at the farm gate. The results were expressed according to the Product Environmental Footprint (PEF) method version 2.0 for 19 impact indicators through SimaPro® software v9.0.35. Five main data categories were considered: water used on the farm, off-farm feeds, energy resources, on-farm feeds, and bedding materials. Dairy farms were ranked into high-, mid-, and low-performing herds according to the average milk yield (>32.6; 25.4–32.6; <25.4 kg milk/cow/d; respectively). Statistical analysis between groups of herds was performed using JMP (JMP® Pro 15.2.0). The environmental impacts of indicators were lower (P < 0.05) in high-performing herds compared with low-performing herds and lower (P < 0.05) for climate change, climate change-biogenic, climate change-fossil, photochemical ozone formation human health (POCP), and eutrophication terrestrial when compared with mid-performing herds. Similar values among groups were observed for acidification, ionizing radiation human health, and ozone depletion potential indicators. The off-farm and on farm feeds categories had the highest share of value of impact indicators. The enteric fermentation and manure handling significantly contributed to greenhouse gas emissions, whereas particulate matter formation and POCP were mainly related to barn management. Results from this research could be helpful in the dairy sector through the completeness of the expected impact indicators evaluated by the PEF method.