The milk fever and mastitis that occur during the colostrum period in dairy cattle cause great damage in the dairy industry by causing a rapid decline in the cattle’s health and decreasing milk production. In order to prevent this, gradual milking (GM), calcium injection with gradual milking (CG), and calcium injection with complete milking (CC) methods are used. However, differences in effectiveness between these methods have not been established. Therefore, this study was conducted to determine the effects of each preventive method on milk fever and mastitis. The results of this study showed that while there was a significant negative correlation of GM with milk fever and mastitis (r = –0.657, p < 0.05), there was no correlation of CG and CC with milk fever and mastitis. The incidence of milk fever was significantly lower in CG and CC than in GM (p < 0.05) but no differences in the incidence of mastitis were observed between the three groups. No significant differences in the rate of recovery from milk fever and mastitis were observed between the three groups. The recurrence rate of milk fever was significantly higher in CG and CC than in GM (p < 0.05), though no differences in the recurrence rate of mastitis were observed. This study showed an inverse relationship between the incidence rates of milk fever and mastitis when calcium injection was not used during the colostrum period. When calcium injections were used, the incidence of milk fever was reduced without affecting the incidence of mastitis regardless of the milking method, but the recurrence rate of milk fever was increased. The results of this study would be useful for controlling blood calcium concentrations and establishing efficient milking strategy in order to effectively prevent milk fever and mastitis in dairy cattle during the colostrum period.

Milk fever is a metabolic disease with manifestation of clinical signs due to hypocalcemia, which usually occurs within 48-72 h after delivery. However, even after a successful treatment of milk fever, recurrence of milk fever may occur, and studies on recurrent milk fever are still lacking. Accordingly, the present study was conducted for the purpose of identifying the characteristics of recurrent milk fever according to farm, season, parity, and dystocia that can cause physiological changes in the mother during peri- and postpartum periods. The analysis results showed that the incidence rate of initial and recurrent milk fever according to breeding farm was 5.7%-14.1% and 3.1%-7.2%, respectively, demonstrating a positive correlation between the initial and recurrent milk fever (r = 0.613, p < 0.01). With respect to season, the incidence rate of initial and recurrent milk fever during summer was 12.3% and 7.5%, respectively, which were significantly higher than that of other seasons (p < 0.05). In addition, the recurrence rate, the ratio of recurrence relative to initial milk fever, was highest during summer with 62.7%. Regarding parity, the incidence rate of initial and recurrent milk fever in 3rd parity was 11.1% and 5.8%, respectively, which was significantly higher than in 1st and 2nd parity (p < 0.05). Furthermore, the recurrence rate in 4th parity was 64.1%, showing a pattern of increase in incidence rate with increase in parity. Finally, there were no differences in the incidence rate of initial and recurrent milk fever according to eutocia and dystocia. The findings indicated that the incidence rate of initial milk fever should be reduced to effectively prevent the recurrent milk fever, while animals with 3rd parity or higher should be expected to occur high rate of recurrent milk fever, especially during summer, and the necessary preparations should be made for intensive treatment of such individuals.