Effect of equine chorionic gonadotropin on pregnancy rates in anestrous dairy cows during a modified PRID-Ovsynch protocol

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, PGF2 alpha 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.

Dergi

MEDYCYNA WETERYNARYJNA-VETERINARY MEDICINE-SCIENCE AND PRACTICE

Yıl

2024

Cilt

80

Sayı

12

Sayfa

635-639

ISSN

0025-8628

DOI

10.21521/mw.6947

WoS UID

WOS:001353646200003