Modeling nitrogen excretions of dairy cattle

Background and Objective

In contrast to the use of fixed table values ​​for the use of crude protein in feeding for the calculation of nitrogen emissions, the systematic data collection established across the board for dairy cattle offers starting points for mapping completed developments over time in nitrogen emissions per cow.

The aim of the joint project is therefore to further develop the procedure for national reporting on ammonia emissions and greenhouse gas emissions by using milk urea values ​​determined routinely in the course of milk checks (milk performance test) or quality tests as a basis for calculations.

Approach

New and improved routine applications for the national emission inventories are to be developed on the basis of comprehensive investigations into the alternative calculation methods, which also include data, findings and results from previous studies.

In addition, existing test data is to be integrated and extensively evaluated for the purpose of providing targeted advice to farmers and supporting measures to reduce emissions. Supplementary feeding studies aim to be able to better assess the existing potential for reducing the amount and type of nitrogen excretion in dairy cattle through feeding optimization. This is done based on current recommendations for nitrogen-efficient feeding and taking into account the effect of adjustments on milk yield and animal health. The inclusion of milk urea values ​​also in the differentiated ration-related analyzes ensures the linking of the two main areas of work and supports the direct practical transfer of the project results for the development and further reduction of nitrogen excretion, especially of urea-N, in the German dairy cattle sector.