Fifty-five Holstein Friesian cows were assigned according to previous milk performance and days-in-milk into control (n = 27) or experimental group (n = 28) on a commercial farm in Czech Republic. Animals were housed in groups including one milking robot in each building. Experimental cows received a partly mixed ration (PMR) with a phytogenic feed additive (PFA) including herbs, spices, essential oils and plant extracts [Digestarom Dairy (3 g/head/day), Biomin Phytogenics GmbH, Germany]. Control cows received PMR without any supplementation during the trial period of 90 d. Both groups received additional concentrates based on wheat, barley, corn and soybean extraction meal according to their milk performance in the milking robots. Feed intake was recorded per group. Feed refusals were evaluated once daily. Milk performance was recorded each time visiting the milking robot, while milk solids were determined 3 times during the trial period. Health status and medical treatments were recorded throughout the trial. Data of daily milk performance were statistically analyzed using the independent t-test (IBM SPSS 21.0). PFA addition in the PMR of dairy cows resulted in a slightly higher dry matter intake (44.23 vs. 43.88 kg/d). The PFA supplemented group produced higher quantities of milk fat (1.27 vs. 1.19 kg/d; P > 0.05), milk protein (1.20 vs. 1.18 kg/d; P > 0.05) and lactose (1.75 vs. 1.67 kg/d; P > 0.05). Animals receiving the PFA showed a significantly higher milk production (35.37 vs. 33.67 kg/d; P < 0.001). Increased daily milk yield and enhanced quantity of milk solids resulted in a superior amount of energy-corrected milk (33.01 vs. 31.89 kg/d; P > 0.05). In conclusion, the tested PFA was able to improve feed intake and milk performance, hence resulting in an increased farm benefit.