Med. Weter. 80
full text
| CIHAN KAÇAR, UMUT ÇAĞIN ARI, SEMRA KAYA, MURAT CAN DEMİR, OĞUZ MERHAN, MUSHAP KURU, SAVAŞ YILDIZ, GÜVEN GÜLBAZ |
| Effect of equine chorionic gonadotropin during a modified PRID-Ovsynch protocol on pregnancy rates in anestrous dairy cows |
| The objective of this study was to investigate the impact of equine chorionic gonadotropin (eCG) injections on progesterone (P4) profiles and pregnancy rates (PR) in Brown Swiss cows with unidentified estrus between days 60 and 120 after parturition. A total of 80 cows were enrolled in the study. All cows had an intravaginal progesterone-releasing device (PRID) inserted for 9 days and received a GnRH injection on day 0. On day 8, PGF2α was administered, the PRID was removed on day 9, and fixed-time artificial insemination (FTAI) was performed 60 hours after PRID removal. Half of the cows (eCG+, n = 40) received a 600 IU injection of eCG when the PRID was removed on day 9, while the other half (eCG–, n = 40) did not. Blood samples were collected on days –10, 0, 8, 9, and during FTAI to measure P4 concentrations. The PR was 37.5% in the eCG+ group and 27.5% in the eCG– group (P = 0.4). At the time of FTAI, the dominant follicle diameter was significantly larger in the eCG+ group (15.5 mm) than in the eCG– group (12.4 mm) (P < 0.001). There was no significant difference in serum P4 concentration between the two groups, except on the day of FTAI, when P4 levels were 0.72 ng/mL in the eCG+ group and 0.94 ng/mL in the eCG– group (P < 0.05). In conclusion, the administration of eCG in addition to synchronization protocols may increase pregnancy rates in cows with unidentified estrus for at least 60 days postpartum. |
| Keywords: Anestrus, Cow, eCG, Progesterone, Subestrus |