Power-cyclic mixing to reduce energy demand in electric dairy feed mixing

The main agricultural equipment for feeding dairy cattle is a standard diesel tractor in combination with a trailed feed mixer, which is powered via the power take-off (PTO) of the tractor. These two machines are now partly replaced by either an all-electric self-propelled mixer or the first commercially available fully electric tractors. This study aims to evaluate a mixing pattern of different PTO speeds that reduces energy input by utilizing the speed-independent efficiency of electric motors and therefore the necessary motor size or battery capacity, without influencing the homogeneous mixing result.As a reference for standard mixing, a measurement series with five tractors (including one full-electric prototype) and three trailed feed mixers was carried out, measuring PTO parameters such as rotational speed (rpm), torque (Nm), and power output (kW). To prove the hypothesis, the same tractor-mixer combinations were then set to a lower engine rpm to simulate the electric motor and were manually adjusted to simulate the power peaks.The results show that a homogeneous mixture of feed can be achieved by power-cyclic mixing. The mixing duration was increased from standard mixing (13:59 min vs. 14:37 min, +4.4%), while the specific energy consumption for rations >2500 kg was reduced by 26.4% from 1.40 kWh/t to 1.03 kWh/t. At the same time, the torque demand for mixing slightly increased to 270.21 Nm from 242.73 Nm (+11.3%).This demonstrates that the concept of power-cyclic mixing can be a practical system for mixing rations for dairy cattle.