Due to topographic and climatic conditions, milk production in Switzerland is mainly based on herbage feeding with only little input of concentrates. This study investigated the effects of a solely herbage-based diet on production, metabolic, and endocrine parameters of dairy cows, and determined the factors affecting the resumption of ovarian cycle postpartum (pp). Twenty-three multiparous Holstein dairy cows (were divided into 2 groups according to their previous lactation yield (4679–10808 kg): a control (C, n = 13) and a treatment group (nC, n = 10) from wk 3 antepartum until wk 8 pp. While C received fresh cut herbage plus additional concentrate according to their estimated energy and nutrient requirements, no concentrate was fed to nC throughout the experiment. Milk yield and DMI were recorded daily. Blood samples were taken weekly and analyzed for IGF-1, glucose, NEFA, and BHBA. Milk progesterone (P4) concentrations were measured every 3 d in morning milk samples (skim milk) by RIA, and considered as resumption of ovarian cycle if the P4 level reached >1 ng/mL. Data were analyzed using mixed models. Plasma NEFA and BHBA concentrations pp were higher in nC (0.82, 1.18 mmol/L) compared with C (0.55, 0.63 mmol/L, P < 0.05). Days to resumption of ovarian cycle was similar between 2 groups (C = 29.8 d, nC = 33.3 d), thus the cows were divided into further 2 sub-groups with earlier/later than the above mean value, and categorized as earlier ovulation (E-OV; C = 22.6 d, n = 7; nC = 21.4 d, n = 6) and delayed ovulation (D-OV; C = 38.3 d, n = 6; nC = 45.2 d, n = 4). In C group, only BCS pp revealed lower in D-OV (2.81) compared with E-OV (3.21, P < 0.05). In nC group, however, D-OV showed lower BW (571 vs. 697 kg in E-OV) and glucose (3.5 vs. 3.6 mmol/L in E-OV + nC), higher BHBA (1.39 vs. 1.04 mmol/L in E-OV + nC) and NEFA pp (0.89 vs. 0.76 mmol/L in E-OV + nC, P < 0.05), suggesting an energy deficiency/stress on lipid metabolism. Other metabolic and welfare-related parameters were similar between E-OV vs. D-OV. In conclusion, in herbage-based feeding system without supplementary concentrate, dairy cows experience a higher metabolic load, which is very likely to affect resumption of ovarian cycle.