책임운영기관 농촌진흥청 국립축산과학원 (로고)

This study aimed to improve the breeding rate in repeat breeder (RB) cows that were unable to become pregnant, despite having a normal estrus cycle. The methods used to synchronize the estrus were the controlled internal drug release (CIDR) PLUS (CIDR device, with estradiol benzoate (EB), PLUS) and the CIDR GnRH (CIDR device and gonadotropin-releasing hormone, GnRH). The study found that the proportion of non-pregnant cows was about 9.1%, which is a relatively high percentage. The study also surveyed the use of breeding cattle as RBs over the past three years and found that the sales rate of fattened cows was about 60.8%, while the rate of management for pregnancy was about 39.2%. The ratio of meat sales was significantly higher (P<0.05). The study then analyzed two methods of estrus synchronization: the CIDR PLUS method and the CIDR with the GnRH method. The results showed that the CIDR PLUS method had a success rate of 56.9%, while the CIDR with the GnRH method had a success rate of 85.2%, which was significantly higher (P<0.05) than the CIDR PLUS method. In conclusion, the study found that RB cows could be effectively bred using the above two methods of estrus synchronization. Among these methods, the CIDR GnRH method was found to be more effective in resuming pregnancy. These findings can help improve the breeding rate of RB cows and increase their productivity.