Gaseous emissions arising from protein production with German Holsteins - an analysis of the energy and mass flows of the entire production chain 2. Emissions and reduction potentials

This study analyses reduction potentials of greenhouse gas and ammonia emissions in protein production with cattle herds using a sensitivity analysis leading to scenarios for practical agriculture. In particular, the effects of varied productive lifespans (number of lactations), diseases and anima losses, increased performance (milk yield, daily weight gain), amounts and types of mineral fertilizers applied, manure management (here restricted to biogas plants) were considered, as these measures are within the range of actions of a farmer and feasible. The survey describes a herd of 100 German Holstein cows with their offspring under steady state conditions. The absolute emissions of the herd as well as the protein-related emissions are quantified. Despite the fact that the main emission sources (for greenhouse gases: methane from enteric fermentation, for ammonia: emissions from animal houses) can hardly or not be altered, the effects reflecting improved production factors have a significant effect if combined. Thus, they may more than compensate the increased emissions resulting from the likely increase in milk yields in the next decade. Measures evaluated result in reduced production areas, decreased nitrogen surpluses, improved nitrogen efficiencies and reduced emissions per unit of product (edible protein) – without additional expenses.