Pasture based production systems should feed as much as possible pasture gras on the total year ration. On 5 austrian farms, changing to pasture based milk production, blood and urine samples of cows were examined to detect changes and exposure in metabolism during the year and lactation. Some changes in blood parameters were detected at the beginning of the pasture. Changes of feeding at the beginning of the pasture showed a decrease in phosphorus in serum. Net-acid-base excretion also showed the burden of feeding a minimum or none of concentrate and the decreased fedding of crude fibre at the beginning of the pasture
