Farm-gate nutrient balances of grassland-based milk production systems with full- or part-time grazing and fresh herbage indoor feeding at variable concentrate levels

Farm-gate balances for nitrogen (N) and phosphorus (P) were used to determine the potential nutrient surplus and nutrient-use efficiency of three grassland-based milk production systems. These were either full-time grazing (FG) or part-time grazing with indoor feeding of fresh herbage with low (IF) or substantial concentrate allowance (IFplus). Data collected over 3 years were used (a) from 3 × 8 commercial dairy farms, and (b) from a controlled...