P.F. Mostert, C.E. van Middelaar, I.J.M. de Boer, E.A.M. Bokkers
The dairy sector is an important contributor to greenhouse gas (GHG) emissions. Foot lesions in dairy cows result in production losses and, therefore, might increase GHG emissions per kg milk. The objective of this study was to estimate the impact of foot lesions in dairy cows on GHG emissions. A dynamic stochastic simulation model was developed to estimate dynamics of digital dermatitis (DD), white line disease (WLD), and sole ulcer (SU), and associated production losses within one lactation. Production losses included were reduced milk production, prolonged calving interval (CI), and culling. Subsequently, a life cycle assessment was performed to estimate the impact of foot lesions on GHG emissions per ton of fat-and-protein-corrected milk (kg CO2e/t FPCM). GHG emissions increased on average by 14 (1.5%) kg CO2e/t FPCM per case of foot lesions (i.e. DD, WLD, and SU combined), ranging from 17 kg CO2e/t FPCM in parity 1, to 7 kg CO2e/t FPCM in parity 5. Emissions of GHGs increased on average by 4 (0.4%) kg CO2e/t FPCM per case of DD, by 39 (4.3%) kg CO2e/t FPCM per case of WLD, and by 33 (3.6%) kg CO2e/t FPCM per case of SU. A prolonged CI explained the majority of the increase in GHG emissions for cows with DD, whereas culling was most important for cows with WLD or SU. DD had the lowest impact on GHG emissions, but the highest prevalence, and, therefore, contributed most to the average impact of foot lesions. This study showed that preventing different types of foot lesions can reduce GHG emissions from the dairy sector. The increasing attention for global warming and possible policies to reduce GHG emissions from agriculture might give dairy farmers another incentive to prevent foot lesions. The impact of foot lesions on GHG emissions, however, can vary among dairy farms, because of differences in prevalence of foot lesions and associated production losses, and in farm management.