Postpartum endometritis is considered as one of the diseases that lead to a potential profit reduction in dairy cows. The aims of the present study were to promote follicle growth by a previously used controlled internal drug release (CIDR) device and to evaluate its effect on the likelihood of recovery and the reproductive performance of clinical endometritis (CE) cows. Endometritis was diagnosed using ultrasonographic examination at 31
3 (Day 0 of the experiment) days in milk, and CE cows were included in one of the three experimental groups according to the presence of a CL on their ovaries. Cows without CL on their ovaries received a reused CIDR device, which was previously used for 14 days (CIDR-14, n ¼ 108), or PGF2a (PG-1, n ¼ 112) on Day 0. In the third group, those with CL on their ovaries received PGF2a (PG-2, n ¼ 107) at the same time. Ovarian structures, serum estradiol and progesterone concentrations were measured on Days 0, 7, and 14. Controlled internal drug release devices were removed, and response to treatment was evaluated in all treated cows on Day 14. Diameters of ovarian follicles were 11.61
0.50, 12.46
0.25, and 18.36
0.60 mm on Day 7 and 11.63
0.58,14.35
0.40, and 21.96
0.77mmon Day 14 in PG-1, PG-2, and CIDR- 14 cows, respectively (P < 0.05). Serum estradiol concentrations were higher in CIDR-14 cows (141.17
1.04 pg/mL) than in PG-1 (116.85
1.05 pg/mL) and PG-2 (119.10
1.05 pg/mL) cows on Day 7 (P < 0.05). Higher progesterone concentrations were observed in PG- 2 cows than in PG-1 and CIDR-14 cows on Days 0, 7, and 14 (P < 0.001). The likelihood of clinical cure was 54.46%, 62.61%, and 64.81% in PG-1, PG-2, and CIDR-14 cows, respectively (P ¼ 0.11). First-service conception risk, days to the first service, calving to conception interval, proportion of cows bred and pregnant by 120 days in milk did not differ among the treated groups (P > 0.05). The cumulative pregnancy risk was lower in PG-1 (77.67%) cows than in CIDR-14 (87.07%) and PG-2 (87.85%) cows (P ¼ 0.02). In conclusion, reused CIDR would be contributed to the treatment of CE by promotion of follicle growth and induction of sustainable sources of endogenic estrogen secreted by the dominant follicle.

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