The aim of this study was to evaluate the effect of herbage allowance of grasslands during the prepartum and postpartum on metabolic and endocrine parameters of beef cows. Forty Hereford heifers were used in a randomized block design and a factorial arrangement of prepartum (fall-winter; high vs. low, PREH vs. PREL) and postpartum (spring-summer, high vs. low, POSTH vs. POSTL) herbage allowance (4 vs. 2.5 kg of DM/kg of BW of annual mean for high vs. low). At the −90, −35, +80 and +160 ± 17 DPP (fall, winter, spring and summer, respectively), BW and BCS was recorded and blood samples were collected. Means from a repeated analysis using a mixed model were considered to differ when P ≤ 0.05. During the prepartum (−90 to −35 DPP; fall and winter) all cows lost BW and BCS, increasing plasma urea, nonesterified fatty acids (NEFA) and β-hydroybutyrate (BHB) while decreasing glucose, insulin and leptin concentrations. During this period, BCS and concentrations of urea were lower and NEFA tended (P = 0.09) to be greater in PREL than PREH cows (4.6vs. 5.0 ± 0.04 units, 7.3vs. 8.1 ± 0.1mmol/L and 1.1 vs. 0.9 ± 0.03 mmol/L for BCS, urea and NEFA, respectively). During the postpartum (spring and summer), BCS and metabolic-endocrine profiles were affected by POST but did not differ due to PRE or the PRE by POST interaction. Cow BCS and plasma glucose and leptin were greater whereas urea and NEFA were less in POSTH than POSTL cows (3.9 vs. 3.6 ± 0.04 units, 2.9 vs. 2.7 ± 0.05 mmol/L; 5.7 vs. 3.8 ± 0.1 ng/mL; 5.2 vs. 5.7 ± 0.1 mmol/L and 0.63 vs. 0.66 ± 0.03 mmol/L for BCS, glucose, leptin, urea and NEFA, respectively) during the lactation period. Plasma urea and NEFA decreased during spring to increase again toward mid-summer when insulin and BHB concentrations also decreased. Metabolic and endocrine profiles of grazing primiparous beef heifers reflected negative energy balance as herbage mass and/or quality decreased during winter gestation or during summer in the late lactation. Improve PRE and POST herbage allowance reduced negative energy balance during the pre and postpartum, respectively.