Feed efficiency is a critical topic in the dairy sector, as it directly impacts the reduction of nutrient losses and plays a significant role in the economics of dairy management. In recent times, the importance of feed efficiency has further amplified due to the pressure to reduce methane emissions, nitrogen losses, and to cope with fluctuating feed and milk prices. It is a challenge to further optimize efficiency and minimize emissions for a sustainable dairy sector while ensuring the well-being of both cows and farmers.