Amazing Grazing: N use efficiency of 60 individual dairy cows under intensive grazing

The Dutch dairy sector aims to improve nitrogen (N) use efficiency (NUE N ) of intensive dairy farms while supporting grazing. To gain insight into the NUE N of intensive dairy farms, we need insight into the NUE N at cow level. We performed a 2 x 2 factorial grazing trial with 60 Holstein Friesian cows (7.5 cows ha -1 ), in which we compared NUE N of individual cows under two grazing systems, i.e. compartmented continious grazing (CCG) and strip grazing (SG) and two levels of dietary rumen-degradable protein balance (OEB), i.e. low and high (a difference of 500 g OEB cow -1 day -1 ). Grass and supplementary intakes and faecal and milk outputs were quantified and analysed for N content, during two weeks in July and September 2016. Results showed a higher NUE N for cows in CCG (39%) compared to cows in SG (36%) in July, due to lower grass (N) intake in CCG. Low OEB showed a higher NUE N (40%) compared to high OEB (34%). Our results are key to exploring strategies to improve NUE N of farms that apply innovative grazing systems.