Analysis of Relationship between Production and Reproduction Traits of Holstein Cattle Population in the Slovak Republic

Is generally known there is antagonistic relationship between production and reproduction traits. We observed this relationship in dataset of 1 197 478 daily milk records of Holstein cows on the first lactation only, first time calved during years 2003-2009. We found increased milk production and prolonged calving interval during this period. We observed highest milk production (7604 kg) on standardized 1st lactation for cows with longest calving interval in compare to cows with shortest calving interval (7079 kg). Positive significant correlation (0.56775, P<0.0001) was found between standardized milk production and calving interval. It means that cows with higher milk production have a prolonged calving interval, which confirms antagonist relationship between production and reproduction traits. Significant negative correlation (-0.27695, P<0.0001) observed between percent of protein production on standardized lactation and calving interval suggests that prolonged calving interval has negative effect on daily protein production (%) in milk. Coefficient of determination between breeding values for milk production and length of calving interval was 0.6434. Following these results we should accept relationship between production and reproduction and include it in process of genetic evaluation of cattle.