Management factors affecting the environmental impact of cereal-based dairy farms

This study aimed to assess the environmental impact (cradle-to-farm gate LCA) of milk production of cereal-based dairy farms in northern Italy and to analyse which traits related to farm management (MAN_F), lactating cows' ration composition (DIET_F), and animal responses (ANI_F) could be identified as main determinants to address specific mitigation strategies. Data originated from 28 dairy farms. The functional unit was 1 kg of fat- and protein-corrected milk (FPCM). Impact categories were global warming (GWP), acidification (AP) and eutrophication (EP) potentials and land occupation (LO). Impact values were analysed with a linear model to test separately the effects of MAN_F, DIET_F and ANI_F variables. One kg FPCM was associated with an average impact of 1.10 kg CO2-eq (GWP), 17.1 g SO2-eq (AP), 6.0 g PO4-eq (EP), and 1.3 m(2)/y (LO). Regarding MAN_F, GWP and LO linearly decreased with increasing values of stocking rate and feed self-sufficiency (FSS), whereas minimum EP was found for intermediate FSS values (50% DM). Regarding DIET_F, GWP linearly decreased at increasing levels of dietary inclusion of cereal silages, whereas AP and EP linearly decreased at decreasing dietary crude protein (CP) content values. Among ANI_F, GWP and EP were quadratically associated with milk yield (MY), evidencing the lowest values at intermediate MY (9100 +/- 477 kg FPCM/cow per 305d-lactation). The GWP, AP and EP decreased with decreasing age at first calving. These results can contribute at drawing good practices for farmers and consultants to promote more environmentally sustainable dairy production while supporting farm functioning and farmers' income.

Automated summary

This study aimed to assess the environmental impact of milk production in cereal-based dairy farms in Italy. The study analyzed the effects of farm management, lactating cows' ration composition, and animal responses on the environmental impact. The results showed that stocking rate and feed self-sufficiency had a linearly decreasing impact on global warming and land occupation, while intermediate feed self-sufficiency values had the lowest eutrophication potential. Increasing dietary inclusion of cereal silages decreased global warming potential, and decreasing dietary crude protein content decreased acidification and eutrophication potentials. Milk yield and age at first calving also had an impact on global warming, acidification, and eutrophication potentials.