Abstract
The aim of this study was to characterise basic reproduction indexes and to investigate the effect of selected factors on values of analysed fertility parameters in cows (100 head) with record lifetime milk yields. The experiments were conducted on Polish Holstein-Friesian Black- -and-White cattle. Cows with lifetime milk yields of min. 100 thousand kg milk were considered record holders. Animals were selected at random from herds covered by performance testing in the Poznań testing region in the years 2003–2016. It was shown that analysed cows with record lifetime milk yields exhibited slightly reduced fertility. The animals had the preferred mean age at first calving and adequate average length of pregnancy. Relatively high numbers of semen doses required for successful insemination resulted in an extended length of calving interval, interpregnancy period and artificial mating service.In the management of dairy cow herds focusing on high lifetime productivity and fertility traits it is recommended to control reproduction so that calvings take place in winter and cows calve for the first time at the age of maximum 27 months.
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