The study was performed on 1194 Black-and-White cows with a high proportion of Holstein-Friesian genes, kept in three tie stalls and two free stalls. Taking into account ECM yield (kg) during the standard lactation period, the cows were divided into the following classes: 1) ≤5000, 2) 5001–7000, 3) 7001–9000, 4) > 9000. The aim of the present study was to determine the effect of cow performance on fertility indices, as dependent on the housing system. Cows kept in the free-stall system produced on average 7161 kg ECM, i.e. by 248 kg more than those kept in the tie-stall system. A significant interaction was found between the housing system and productivity levels as for fertility-related parameters. In tie-stall housing an increase in milk yield was accompanied by worse fertility traits, whereas in free-stall housing there was no significant correlation between performance and fertility. Free-stall housing weakened the negative influence of high productivity on the reproductive functions of cows.

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