The aim of the study was the analysis of the effect of calving season on the course of parturition and rearing results of Polish Holstein-Friesian calves of Black-and-White strain from birth to 3 months of age. Easy calvings (1;2) predominated on the farm. In spring, they accounted for 91.2% of all calvings occurring in this season. The respective values for summer, winter and autumn were 89.7%, 88.6% and 87.6%. The highest mean birth weight was characteristic of calves born in winter (40.8 kg and 44.2 kg for heifer calves and bull calves, respectively). The highest mean daily body weight gains in the whole rearing period were achieved by heifer calves born in winter (704 g) and bull calves born in spring (750 g). In the group of heifer calves and bull calves, statistically significant differences during the analysed rearing period were found (P≤0.01, P≤0.05). The highest percentage of ill calves was found in the autumn-winter season and the lowest one in spring and summer.

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