EN
The aim of the study was to investigate the physiological pattern of haematological variables and to acquire reference intervals for calves in different age periods. Sixty-five Holstein Friesian calves from two dairy farms were serially sampled from birth to the age of 24 weeks. Red blood cell count (RBC), haemoglobin concentration (Hb), mean corpuscular volume (MCV), haematocrit (PCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), number of platelets (PLT), and white blood cell count (WBC) were measured in blood samples. The health status of the calves was monitored. The age influenced significantly the values of all haematological variables (P<0.001). The effect of farm was significant for RBC (P=0.048) and MCHC (P<0.001), other variables did not differ significantly between farms. The temporal dynamics of RBC, Hb, and PCV values was harmonised. A progressive reduction in the values occurred over the first weeks of life; the lowest values were established at the age of 5 to 6 weeks. The reference intervals of haematological variables were calculated for three age groups of calves; 1-4 weeks, 5-8 weeks, and 12-24 weeks of age.