The objective is to investigate the effect of the extended lactation on climatic and environmental load as well as economic result at farm level. Feed intake and production data (WP2+3) will be used to estimate annualized emissions of green house gases, N and P from cows at different feeding and reproduction strategies, and the effects will be modelled both at farm level and at product level by use of life cycle assessment (LCA) both at farmgate and in relation to the processing efficiency in the chain towards the consumer. The production results will further be used to evaluate the economic farm result and to investigate the long term effect of the extended lactation on the genetic improvement in the herd.

Expected outcome:
1) Estimation of a lower the green house gas emission from dairy production differing in feeding and reproduction strategies 2) Evaluation of the economic return from these systems at farm level and 3) analysis of the possible impact on the development of the genetic merit in the herd 4) a PhD.