Combining grazing and high mineral efficiency

In the Netherlands many farmers assume pasture grazing for dairy cows to be less efficient in terms of mineral utilisation than indoor housing systems. The gross annual grass yield is assumed to be lower as well. Since 2016, Dutch dairy farmers are obliged to use the ANCA-tool (Annual Nutrient Cycling Assessment) to show the mineral efficiency of their farms. Farmers claim that pasture grazing leads to a worse ANCA performance than indoor housing. This claim puts pressure on pasture grazing. Therefore, a study was performed to analyse the effect of grazing on mineral efficiency. The analysis of a dataset containing 2,725 ANCA results of Dutch dairy farms showed that the average phosphorus and nitrogen excretion for farms that apply pasture grazing for their cows for less than 1000 hours cow-1 yr-1 were not significantly different from the indoor housing systems. On farms that apply grazing for more than that, the mineral excretion was higher. Measures were identified to improve the mineral efficiency, e.g. less young stock, feeding additional roughage and concentrate low in protein and phosphorus. This study shows that farms with restricted grazing can combine grazing and mineral efficiency.