ABSTRACT:The aim of this study was to determine the impact of the length of calf sucking milk from its own mother on calf growth at the age of 3 months and milk yield of mothers. We tested a hypothesis that the nursing of calves by their own mothers increases the body weight of calves and decreases the milk production. 50 Holstein primiparous cows and their calves were divided into three groups according to the sucking length of calves: 7 days (A), 14 days (B) and 21 days (C). All calves suckled mother's colostrum and milk while mothers were milked twice per day. After weaning from mother calves were kept in individual hutches until 56 days of life, and then in group housing pens. In the period from birth to weaning the calves of group A reached the lowest and the calves of group C the highest daily gains (0.35 kg, 0.46 kg, 0.54 kg; P < 0.01). The lowest gain was recorded in animals of group A (0.55 kg) and the highest gain was reached by calves of group C (0.74 kg) for the period from birth to three months of age. For the first 305 days of lactation cows of group A produced insignificantly more milk than group C (7356.5 kg, 6779.2 kg, 6663.9 kg). A significant difference in milk production was recorded only during the first seven months of lactation (5494.5 kg, 5041.9 kg, and 4872.3 kg; P < 0.05). The long stay of calves with their mothers influences the growth of calves positively, but the milk production of mothers may decrease. Therefore, the stay of calves with the dam within 21 days after birth is not recommended for high-yielding dairy cows.