The impact of various feeding strategies for dairy cattle on nitrogen excretion, ammonia and greenhouse gas emissions: Dutch case study using the dairy cow model and the annual nutrient cycling assessment model

The current report describes the results of Feed4Foodure III, work package 5: a modelling study to gain insight in the potential effects of different scenarios on greenhouse gas and ammonia emission from dairy cow farms. The environmental impact (N and P utilization, emissions of NH3, CH4, CO2-equivalents) were analysed on farm level. A connection was made between the Dairy Cow Model and the Annual Nutrient Cycle Assessment model (KringloopWijzer). The simulated scenarios included increased fresh grass intake, increased grazing time, herb rich grassland, herb rich grassland with increased grazing time and four low protein scenarios. Increased fresh grass intake and increased grazing time had a limited impact on ammonia emissions and GHG emissions compared to the basic scenario. Herb rich grassland resulted in a minor reduction of GHG emissions. Low protein scenarios showed there is a high potential to reduce ammonia emissions although it may negatively influence milk yield. Total GHG emissions also decreased, however, enteric methane emissions increased.