Abstract: [Objective] This study aimed to investigate the effects of different doses of carbetocin on the therapeutic efficacy for retained placenta,conception rate,and colostrum yield in dairy cows,in order to provide a theoretical basis for its rational clinical application in veterinary practice. [Method] A total of 120 healthy Holstein cows were selected and randomly divided into 4 groups. The control group received an intramuscular injection of 10 mL normal saline within 10 minutes postpartum. The low-,medium-,and high-dose groups received intramuscular injections of carbetocin at doses of 250,300,and 350 μg per head,respectively. The placental expulsion status and time,first-service conception rate,colostrum yield,and serum levels of inflammatory factors （IL-1β,IL-6,TNF-α） were observed and recorded for each group. [Results] The results showed that as the dose of carbetocin increased,the incidence of retained placenta gradually decreased. The incidence in the medium- and high-dose groups was significantly lower than that in the control group （P < 0.05）. The first-service conception rate was significantly higher in all treatment groups compared to the control group. Colostrum yield showed an increasing trend with dose,but the differences were not statistically significant. The serum levels of inflammatory factors were significantly lower in the medium-dose group compared to the control group. [Conclusion] This experiment indicates that carbetocin can effectively promote placental expulsion,improve the conception rate,and may reduce postpartum inflammatory responses. A dose of 300 μg per head is recommended for clinical use as an appropriate dose that balances efficacy and cost-effectiveness.

Key words: carbetocin, dairy cows, retained placenta, conception rate, colostrum yield, inflammatory factors