Sustainability of European cattle farming: Status Quo and ways forward analysed with a farm-level optimisation model

Europe is among the largest cattle producers worldwide, contributing to food security and the economy. However, the recent public debate has questioned existing production systems due to their adverse environmental effects, such as their contribution to climate change. This thesis assesses the sustainability of European cattle farms and identifies technological and political levers to improve them towards more sustainable means of production. For this purpose, the bio-economic optimisation model FarmDyn is applied. <br> First, the model is used for a life cycle sustainability assessment of typical European bull beef production systems. Here, it is revealed that using dairy breed calves leads to favourable environmental indicator values and less work time spent on production due to the partial allocation of impacts towards dairy production. For example, systems using dairy breeds for fattening reduce global warming potential (GWP) by up to 60% compared to beef breeds. In contrast, beef-breed systems have higher profitability due to higher beef prices despite higher production costs. <br> In a second application, the before-established framework is used to test fast rotational grazing (FRG) and crossbreeding (CB) regarding their ability to improve the sustainability of beef production. FRG increased farm profit and production workload through additional fencing efforts. CB with dairy cows and beef bulls was found to decrease GWP, while CB with early-maturing beef breeds showed only limited improvement. Redesigning farms using CB with dairy cows, FRG, and a stocking rate adjusted to the land's carrying capacity could substantially decrease the feed-food competition. <br> The third application estimates marginal greenhouse gas abatement cost curves for Norwegian dairy and dairy-beef farms. The findings indicate that up to 5% abatement compared to current emission levels of the farms is achievable at costs below 200€ per t CO2eq. The most effective measure is optimising animal feed rations towards higher energy density, potentially saving 8% to 20% of emissions from enteric fermentation. Other cost-efficient measures include transitioning from fossil fuels to biofuels and adopting advanced manure application technology. However, higher abatement efforts are realised through herd size reductions, starting with bulls for beef production, as they are less profitable. <br> Given cattle production's prevalent burden on the environment, its contribution to the economy, and its social influence, political action is needed to carefully balance environmental impacts, policy goals, and farmers' interests.