To fulfill the high-energy requirements of early lactating cows, concentrate-rich diets are fed. However, high amounts of concentrate can negatively affect rumen as well as liver health. Previously, clay minerals have shown potential to counteract the negative effects of high-concentrate feeding. Therefore, the aim of this study was to investigate if a clay mineral-based mix (CM) can counteract negative effects of a concentrate-rich diet in dairy cows. Twenty-four lactating Simmental cows (51 ± 23.8 DMI, 8 primiparous, 16 multiparous) were fed a baseline diet for 2 weeks (BASE1–2, 40% concentrate, 60% roughage; DM base) followed by a high-concentrate diet for 4 weeks (HC1–4, 60% concentrate, 40% roughage; DM base). Animals were either assigned to the group receiving the diet with CM addition (n = 12 cows) from BASE2 onwards, or to the group with no additive (CON; n = 12 cows). Fecal as well as blood samples were collected weekly during the whole trial. Fecal pH was measured by using a hand-held pH meter. The liver enzymes activity of aspartate-amino-transferase (AST), glutamate-dehydrogenase (GLDH), and gamma-glutamyl-transferase (GGT) was measured in the plasma with a fully automated analyzer for clinical chemistry. Haptoglobin (Hp) concentration in the plasma was measured with a commercially available ELISA kit. Statistical analysis was performed by using the MIXED procedure of SAS, including diet, group and parity, as well as a possible interaction between them as fixed effects. HC caused a decrease in fecal pH and an increase in liver enzymes in all cows (P < 0.05). Multiparous cows receiving CM had a higher fecal pH during HC4 (P < 0.05). Furthermore, primiparous cows receiving CM showed a decrease of GLDH during HC1 and GGT during HC1 and HC4 (P < 0.05). In addition, supplementation of CM resulted in a decreased Hp concentration in primiparous cows during BASE2 (P < 0.05). Data suggest that HC-feeding negatively affected fecal pH as well as liver health. Furthermore, CM may alleviate the severity of high-concentrate feeding by increasing the fecal pH as well as reducing the activity of liver enzymes.