This study determined diagnostic threshold of polymorphonuclear cells (PMN) for cytological endometritis (CEM) and its impacts on reproductive performance in dairy cows. Uterine cytology using 407 Holstein cows was performed at 4 weeks postpartum and proportion of endometrial cells and PMN was evaluated. A receiver operating characteristics curve was built to assess the cutoff level above which the PMN proportion affected the hazard of pregnancy by 200 days postpartum. The cutoff level for CEM was set at ≥14% PMN (sensitivity = 31.3%, specificity = 81.7%, P < 0.05). Cows with CEM had a lower probability of resumption of cyclicity (OR = 0.58 P < 0.05) and lower hazard of pregnancy by 200 days postpartum (hazard ratio = 0.58, P = 0.0001) than cows without CEM. Cows with CEM tended to have a lower probability of pregnancy to the first insemination (OR = 0.65, P < 0.1) and a greater number of insemination per conception (2.3 vs 2.2, P < 0.1) than cows without CEM. In conclusion, the threshold level of PMN was 14% to define CEM at 4 weeks postpartum and CEM decreased subsequent reproductive performance in dairy cow

• Soo Chan Lee(College of Veterinary Medicine, Chungbuk National University)
• Jae Kwan Jeong(College of Veterinary Medicine, Chungbuk National University)
• In Soo Choi(College of Veterinary Medicine, Chungbuk National University)
• Hyun Gu Kang(College of Veterinary Medicine, Chungbuk National University)
• Young Hun Jung(National Institute of Animal Science, RDA)