The concept of extended lactation is supposed to improve cow health and productivity and at the same time reduce greenhouse emission from high-yielding organic dairy cows in a product perspective. This effect is achieved through fewer calvings per year and hence a production of fewer replacement heifers, which then reduces the annual herd requirement for feed. We believe that the average milk yield per feeding day – days lactating plus days dry – per cow will be unchanged. However, this requires that the average cow will have to produce milk for a longer timeframe, and thus they will become older before being culled. We believe this will be a derived effect of the improved cow health as the majority of disease incidences occur around the time of calving. An on-going project at Aarhus University aims at characterising those cows, which can, and those cows which cannot produce milk for extended period of time before estimating the overall herd effect on farm economy and greenhouse gas emissions
