Supplementation of gluconeogenic precursors in postpartum dairy cattle diets may improve production performance and decrease incidence of metabolic disorders related to negative energy balance. The objective of this trial was to examine the effect of fermented ammoniated condensed whey supplementation on hyperketonemia incidence in transition dairy cows. Holstein cows were individually housed in a tie-stall facility from 28 d prepartum to 45 d postpartum. Cows were blocked by expected calving date and randomly assigned to control (ctl; n = 20) or GlucoBoost (GB; Fermented Nutrition; n = 19). All cows received the same high-energy prepartum ration precalving to achieve postpartum hyperketonemia incidence consistent with industry averages. Cows began treatment rations (GB 0.9 kg AF/day replacing DM equivalent in ctl) on the day of calving. Hyperketonemia incidence was calculated from blood samples collected on d 1, 3, 5, 7, 9, 11, 14 and 17 after calving. Categorical data were analyzed by logistic regression (GLIMMIX, SAS) fitting a binary distribution response. Continuous variables were analyzed with the MIXED procedure of SAS. Models containing the fixed effect of treatment (GLIMMIX) or treatment, time, and the interaction of treatment x time (MIXED) and random effects of block and cow(block × treatment). Supplementation did not alter (P > 0.54) milk volume (41.1 vs. 42.2 ± 1.53 kg, ctl vs. GB), fat, protein, or lactose yield. Cows supplemented with GB had a numerically reduced hyperketonemia incidence (60.0 vs. 36.8 ± 11.28%, P = 0.17). Body weight change (−69.7 vs. −60.4 ± 8.78 kg, ctl vs. GB) and body condition score change (−0.39 vs. −0.30 ± 0.052 units, ctl vs. GB) from calving to 45 d did not differ (P > 0.25) by treatment. Concentration of NEFA differed over time but was not affected (P = 0.70) by treatment. Supplementation of GB did not alter body tissue mobilization or milk production, but reduced hyperketonemia incidence by 1.6 times. This suggest that GB may have altered hepatic metabolism to improve postpartum metabolic disease incidence.