Association between age at first calving and milk production in first lactation on longevity traits in Holstein cows

The objective of this research was to determine the association between age at first calving (AFC) and milk production in the first lactation of longevity traits for Holstein cows. The research was conducted on 2307 cows raised on 4 farms in AP Vojvodina. The cows were culled in the period from 2017 to 2018. The cows belonged to the group of Holstein Friesian breed of cattle. Cow longevity was observed using three parameters: number of lactations (NL), lifetime milk yield (LMY) and length of productive life (LPL). The research involved the influence of the farm on which the animals realized their production, the season of first calving. A mean value obtained for the length of productive life in the analysed population was 1207 days (3.30 years on average). During this period the animals on average realized 2.45 lactations and produced on average 18798 kg milk. All studied traits showed a high level of variability. From these data, the study sought to determine the influence of factors on the traits of longevity, our research present that studied factors showed high statistical significance on these traits except in the case of the season of first calving where a statistical significance effect wasn?t observed. The season of first calving did not affect the animal traits for longevity and, generally, didn?t affect the calving interval. Regarding the obtained correlation data between age at first calving and length of productive life, it can be concluded that belated AFC leads to reduced reproductive performance.