An 18 week field trial was conducted on a commercial dairy in southwest Minnesota equipped with 2 Lely robotic milking units. This study was designed to evaluate the response of feeding a proprietary essential oil and cobalt product (EOC) on the lactational performance and nutrient digestibility of lactating Holstein dairy cows. Cows were divided between 2 pens (57 ± 2 cows and 59 ± 3 cows for treatment [EOC] and control [C] pens, respectively), based on cow parity (2.65 ± 1.52 and 2.33 ± 1.20), days in milk (DIM) (184 ± 103 and 154 ± 94.2), and milk production (35.4 ± 11.3 kg/d and 36.9 ± 11.3 kg/d) before study initiation. Cows were fed either an EOC or C total mixed ration (TMR) 2x/d. Cows fed the EOC averaged 2.72 ± 0.11 milkings/d and cows fed C averaged 2.80 ± 0.13 milkings/d. Production data were collected daily from Lely Time for Cows (T4C) robotic milking software and was reduced to weekly observations for each cow. Fecal samples were collected weekly from each pen based on a composite from 15 cows. Weekly TMR samples were collected from EOC and C pens and were composited monthly. Milk samples were collected once every 2 weeks from all cows and were analyzed for milk components and somatic cell counts (SCC) by the Dairy Herd Improvement Association (DHIA). Daily milk production was not different (P = 0.26) between EOC and C fed cows, but was numerically greater for cows fed EOC (41.9 ± 1.91 kg/d) than cows fed C (38.8 ± 2.05 kg/d). The deviation in milk yield was greater (P = 0.01) for cows fed EOC (0.42 kg/d) than cows fed C (−0.75 kg/d). Total-tract NDF digestibility was numerically greater (P = 0.36) for cows fed EOC (54.4% NDFD) than cows fed C (50.6% NDFD). Cows fed EOC had lower (P = 0.0002) milk urea nitrogen (MUN) (15.2 ± 0.14 mg/dL) than cows fed C (15.9 ± 0.14 mg/dL). Feeding the proprietary EOC product on a commercial dairy operation, which used robotic milking units numerically increased milk production and total-tract NDF digestibility.