Abstract
This study was carried out to exhibit the influence of different environmental factors including the seasonal effects on milk yield and fertility of Holstein Cows reared in Afyonkarahisar. The milk yield and fertility data of 175 lactating Holstein cows born in 2003 were used as study material of this research. The results regarding the average values of 305 days milk yield, lactation length, dry period, age at first gestation, service period, calving interval, gestation length and insemination number per gestation were 6884.111 kg, 358.571 days, 66.69 days, 17.13 months, 26.17 months, 146.519 days, 424.804 days, 274.026 days and 1.317 respectively. The effect of enterprise groups and calving age on 305 days milk yield was found significant while the effects of lactation turn, calving season, age and year were insignificant. The differences between the enterprise groups were significant in term of service period, while the differences regarding enterprise, lactation turn, calving age and year averages were insignificant. The differences between the seasonal group means were significant while the effect of enterprise, lactation turn, calving age and year was insignificant. Significant differences were determined in enterprise, lactation turn, calving age and year groups in term of insemination per gestation number, but the differences for calving season were insignificant. Consequently, it was observed that different environmental factors had significant effects on most of the examined milk and fertility parameters. However, the divergence in the values of fertility from optimum values made us think about the problems in herd management.