The studies were carried out on the population of 14215 cows. The first lactation yield, in kg of FCM, significantly differentiated both the yields of subsequent lactations and the indices of life performance of the cows. In highproduction herds (with more than 5000 kg FCM), it is justifiable that the requirement should be met for heifer cows to reach the yield that would balance the costs of their rearing (50006000 kg of milk), as their high productivity during the first lactation positively influences their life performance, which is important especially from the perspective of the short period of productive life. In other herds, in the case of highly productive heifer cows, the lower the herd production level, the more intensive the following effects should be expected: decrease in the yield of subsequent lactations, lower overall life performance, fertility deterioration, lower number of born calves and shorter productive life.
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