Dutch Dairy Farmers Can Cut Emissions Without Losing Milk Production, Wageningen Study Shows
Wageningen, Tuesday, 10 March 2026.
A groundbreaking multi-year study reveals that reducing protein in cattle feed by just one percentage point dramatically cuts nitrogen excretion by 27% while maintaining milk production levels, offering dairy farmers a practical path to meet climate targets without sacrificing profitability.
Comprehensive Multi-Year Research Design
The research, conducted by Wageningen University & Research (WUR), represents one of the most comprehensive studies of its kind in dairy farming sustainability [1]. The multi-year investigation, which concluded in March 2026, monitored 64 dairy cows through two complete lactations of at least 44 weeks each [1]. This extensive timeline allowed researchers to capture the full impact of dietary modifications across different seasonal conditions and lactation cycles. The study was jointly funded by three key industry organizations: the Vereniging Diervoederonderzoek Nederland (VDN), LVVN, and het Melkveefonds, demonstrating strong sector commitment to finding practical emission reduction solutions [1]. The research was conducted at the Dairy Campus in Leeuwarden, Netherlands, providing a controlled environment for precise measurement and monitoring [2].
Strategic Protein Level Optimization
Researchers tested three distinct protein concentration levels to identify the optimal balance between emission reduction and production efficiency [1]. The low-protein group received feed containing 133 grams of raw protein per kilogram of dry matter (g RE/kg DS), while the medium and high-protein groups received 143 g RE/kg DS and 154 g RE/kg DS respectively [1]. Critically, all three protein levels tested were significantly below the Dutch national average of 161 g RE/kg DS recorded by CBS in 2024 [1]. This strategic approach allowed researchers to explore emission reduction potential while staying within practical farming parameters. The study revealed that reducing protein content from 154 g/kg DS to 143 g/kg DS maintained both feed intake and milk production levels, while a further reduction to 133 g/kg DS resulted in decreased feed consumption and milk output [1][2].
Dramatic Nitrogen Emission Reductions
The nitrogen emission results demonstrate the significant environmental potential of optimized protein feeding strategies [1]. During the first lactation period, nitrogen intake varied substantially across the three groups: the low-protein group consumed 462 grams per day, compared to 548 g/d and 590 g/d for the medium and high-protein groups respectively [1]. The most striking findings emerged in nitrogen excretion patterns, particularly through urine. The low-protein group excreted just 105 grams of nitrogen per day via urine, representing a 43.243 = 43% reduction compared to the high-protein group’s 185 g/d [1]. The medium-protein group achieved 146 g/d of nitrogen excretion, demonstrating a clear correlation between dietary protein levels and nitrogen waste [1]. Furthermore, nitrogen utilization efficiency for milk production reached 34.8% in the low-protein group, compared to 31.9% in the high-protein group, indicating more efficient nutrient conversion [1].
Methane Emission Benefits and Production Impacts
The study also documented significant methane emission reductions alongside the nitrogen benefits [1]. During the first lactation, methane excretion measured 442 grams per day in the low-protein group, compared to 484 g/d and 488 g/d in the medium and high-protein groups respectively [1]. This represents a 9.426 = 9.4% reduction in methane emissions when comparing the lowest to highest protein levels. However, the production trade-offs became apparent when examining detailed milk output data [2]. Cows in the low-protein group (13.3%) consumed 21.7 kg of dry matter daily and produced 29.9 kg of milk, while the medium-protein group (14.3%) consumed 23.9 kg of dry matter and produced 33.8 kg of milk per day [2]. The high-protein group maintained the same dry matter intake as the medium group but achieved slightly higher milk production at 34.4 kg per day [2]. Fat and protein corrected milk production revealed more pronounced differences: 31.3 kg per day for the low-protein group versus 35.8 kg and 36.8 kg for the medium and high-protein groups respectively [2].