The aim of this study was to determine factors affecting passive transfer in heifer calves born within 1 yr and how passive transfer influences rearing to the period of first insemination under commercial dairy farm conditions. Calves were divided into 4 groups based on serum immunoglobulin concentrations at 30 to 60h of life (<5, 5–10, 10–15, and >15g/L, respectively in groups 1 to 4). Calving ease, dam parity, calf body weight at birth, calf vitality, quality of colostrum, time and volume of first colostrum fed, morbidity rate and intensity of illness, growth rate, and age and efficiency of first insemination service were recorded. Plasma fibrinogen, and serum γ-globulin, IgG1, IgG2, IgM, and haptoglobin were estimated at 30 to 60h and again at 21 to 28 d of life. Additionally, the immunoglobulin index (IIg3–4) was calculated. The main cause of FPT and PFPT in the calves was poor vitality associated with dystocia and low volume of ingested colostrum. The calves born to primiparous cows were more endangered than those born to multiparous cows. The morbidity and intensity of disease course were lowest in heifer calves with serum Ig concentration exceeding 10g/L at 30 to 60h of life; these calves did not become ill before d 14 of life. Calves with >15g/L γ-globulin in serum avoided respiratory tract infections. The immunoglobulin index was lowest (0.61) in calves from group 4 and highest in calves from groups 1 and 2 (1.44 and 0.88, respectively). The suitability of this index as well as haptoglobin determination was confirmed in prediction of morbidity risk and disease intensity in growing heifer calves. Heifers with serum γ-globulin levels >10g/L at 30 to 60h of life showed better health status and reached body weights allowing first insemination sooner.