High-forage diets for close-up dairy cows are gaining popularity and are increasingly perceived to provide health and production advantages. After calving cows are typically transitioned to a high-energy diet but it is not clear how this transition affects their health and behavior. Our objective was to test the effect of maintaining cows on a high-forage diet for 3 wk after calving, versus switching to the conventional high-energy diet. Sixty-eight Holstein dairy cows (21 primiparous and 47 multiparous cows) were all fed the same high-forage prepartum diet. After calving, cows were moved to a postpartum pen for 21 d and randomly assigned to feed bins according to their respective treatments (Straw TMR: STMR vs. Control TMR: CTMR). After 21 d, all cows were moved to a new pen and fed CTMR. An electronic feeding system continuously monitored individual feeding behavior and intake. Rumination time was recorded using data loggers. Blood was sampled twice per week and tested using the β-hydroxybutyrate (BHBA) Precision Xtra kit. Cows were considered subclinically ketotic (SCK) if BHBA was ≥1.0 mmol/L in the first wk postpartum or ≥1.2 mmol/L from d 7 to 35 postpartum. Milk yield was recorded daily. Data were analyzed using the Mixed and Genmod procedures of SAS; cow was treated as a random effect and period (wk or d) as the repeated measure. Fresh cows fed STMR had lower DMI, fewer meals, spent more time at the feed bunk and had a slower feeding rate (P ≤ 0.02). Rumination time of cows fed STMR was higher than cows fed CTMR (P = 0.04). Cows fed STMR had higher BHBA concentrations during wk 3 (P = 0.03) and were 4.9 times more likely than the CTMR group to develop SCK by wk 3 (odds ratio = 4.9, 95% confidence interval = 0.95 - 25.47, P = 0.06). Over the first 35 d of lactation, cows fed CTMR produced more milk than those fed STMR (33.3 ± 1.0 vs. 30.7 ± 1.0 kg/d; P = 0.03). These results indicate that maintaining cows on a high-forage diet after calving can have detrimental effects on energy balance and cow health.