INFLUENCE OF GROWTH AND DEVELOPMENT INDICATORS OF HOLSTEIN HEIFERS ON THEIR PRODUCTIVITY AFTER THE FIRST CALVING

The study analyzed the impact of growth and development parameters of Holstein heifers on their subsequent productivity after the first calving. The material was based on records of first-calf cows (n = 570) raised at STOV “Promin” (Mykolaiv region). It was found that the live weight of heifers at birth had a statistically significant effect on the lactation duration (P = 0.047) and total milk yield per lactation (P = 0.002), whereas the relationship with the 305-day lactation yield was not significant (P = 0.162). The analysis showed no statistically significant effect of the average daily gain of heifers from birth to 90 days of age on lactation duration (P = 0.161), total lactation yield (P = 0.700), or 305-day yield (P = 0.413). The dependence of primiparous productivity indicators on live weight at 90 days of age also revealed no statistically significant influence on lactation duration (P = 0.826), total lactation yield (P = 0.487), or 305-day yield (P = 0.128). According to the results, the average daily gain of heifers from birth to insemination had no significant effect on lactation duration (P = 0.306), total lactation yield (P = 0.907), or 305-day yield (P = 0.935). The live weight of heifers at 250 days of age did not have a statistically significant effect on lactation duration (P = 0.141), total lactation yield (P = 0.220), or 305-day yield (P = 0.189). The average daily gain of heifers from birth to insemination had no significant effect on the duration of the dry period (P = 0.167) or the calving interval (P = 0.868). Similarly, the live weight of heifers at 250 days of age did not significantly affect the duration of the dry period (P = 0.278) or the calving interval (P = 0.374).