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In the Netherlands the calculation tool “Annual Nutrient Cycling Assessment” abbreviated as “ANCA” is used by Dutch dairy farms as a tool to estimate the efficiency of dietary phosphorus and nitrogen utilization on farm level. In this tool the Dutch Net Energy system for dairy cattle, the so called VEM system, is used to calculate the feed intake of the cows and has an import role in calculating the utilization efficiency of dietary nitrogen and phosphorus. The present VEM system has been developed in 1975 and recent studies indicate that the energy requirement for maintenance in modern Holstein Friesian (HF) cows is around 30% higher than assumed in the VEM system. The goal of this study was to determine the energy requirements for maintenance and milk production for modern day HF cattle. Estimated metabolizable energy requirements for maintenance for dry and lactating dairy cattle were, respectively, 614 and 566 KJ/d/kg BW0.75. The efficiency in which metabolizable energy was converted into milk energy was 0.634. It is concluded that both the estimated metabolizable energy requirement for maintenance for dry non-pregnant cows and for lactating non-pregnant cows is substantially higher than the metabolizable energy requirement of 488 KJ/d/kg BW0.75 that is presently used in the Dutch VEM system.
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