We hypothesized that cows grazing stockpiled tall fescue (STF) during late gestation would have increased nutrient intake compared with cows fed summer-baled hay, which would result in increased nutrient availability for fetal growth and development. Forty-eight multiparous, spring-calving crossbred beef cows were allocated by BW (683 ± 16 [SE] kg), BCS (5.8 ± 0.1), age (5.6 ± 0.4 yr), and expected calving date (average = February 18) to 1 of 2 forage systems beginning on d 188 ± 2 of gestation. Forage systems were: 1) strip-grazed endophyte-infected STF (59.7% NDF, 12.3% CP; DM basis; 80.4% utilization) in 4.05-ha pastures (n = 4), or 2) ad libitum endophyte-infected tall fescue hay (64.9% NDF, 6.2% CP; DM basis) fed in uncovered drylots (18 m × 61 m, n = 4). Cows remained on their respective treatments until calving. Jugular blood samples were obtained from cows on d 0 (baseline; d 188 of gestation), 35 (d 223 of gestation), and 77 (d 265 of gestation) for determination of serum blood urea nitrogen (BUN) and plasma glucose. Data were analyzed using a mixed model containing effects of treatment, sampling day, and their interaction, where sampling day was used as a repeated measure. Pasture or drylot was considered the experimental unit. During late gestation, there was a forage system × day interaction (P < 0.001) for serum BUN concentrations. Baseline serum BUN concentrations did not differ (P = 0.95) between forage systems. On d 35 and 77 of the study, cows grazing STF had greater (P < 0.001) serum BUN concentrations than cows fed hay only. There was no treatment × day interaction (P = 0.57) for plasma glucose, but cows grazing STF tended to have greater (P = 0.11) glucose concentrations than cows consuming hay. Additionally, as gestation progressed, plasma glucose increased (P = 0.02). We conclude that cows grazing stockpiled tall fescue had increased circulating BUN and glucose concentrations due to increased nutrient intake during late gestation, which may affect fetal development and subsequent calf performance.