The economic and environmental consequences of grazing strategies on dairy farms

In response to an increased global demand for food, dairy production systems have been intensified in North-West Europe over the past decades leading to less grazing and more supplementary feed. Combining fresh grass intake with supplementary feed can be challenging, since an incorrect balance can result in inefficient grassland use and reduced milk yield. Improving the fresh grass intake of grazing systems can reduce resource consumption and, thereby, potentially improve the economic and environmental performance of those systems. In this study we quantified the technical performance of grazing strategies in order to determine their economic and environmental consequences. Fresh grass intake can be improved by allocating the right amount of fresh grass to the herd. To this end, a reliable estimate of the fresh grass allowance is essential. First, we tested whether the commonly used rising plate meter can be used to quantify fresh grass allowance across grazing systems, based on one generic calibration equation. Our results indicate that, despite relatively large differences in pre- and post-grazing heights and period of regrowth, one generic calibration equation can be used across grazing systems. Second, we showed the importance of correcting the fresh grass allowance for the formation of rejected patches surrounding dung. Third, we found a more labour-friendly method to quantify fresh grass allowance, which can take into account rejected patches, using drone technology. Finally, we modelled the economic and environmental consequences of improved fresh grass intake and formulated keys to sustainable grazing.