Clinical and Endocrine Response of Dairy Cows with Ovarian Cysts to GnRH and PGF2α

Abstract

Thirty-two Holstein and Guernsey cows diagnosed as having ovarian cysts via rectal palpation were assigned according to breed to one of four grops (eight cows/group). Treatments were: Group I — sterile water; Group II — 100 μg gonadotropin releasing hormone (GnRH); Group III — 25 mg prostaglandin F2α (PGF2α; 33.5 mg PGF2α Tham salt); and, Group IV - 25 mg PGF2α 9 days following 100 μg GnRH. Positive response (ovulation detected within 30 days following initiation of treatment) for cows in Group II (6/8), III (5/8) and IV (7/8) was not different; however, all were different (P<.01) from Group I (0/8). Mean time from initiation of treatment to estrus or silent estrus (the day prior to ovulation without estrus) was less (P<.05) in Group III (5.6 ± 2.4 days) than Group IV (12.3 ±1.2 days) and both Groups III and IV had fewer (P<.01) days to estrus or silent estrus than Group II (19.0 ±1.5 days). In the cows that responded to treatment in Groups II and IV, an increase (P<.05) in progesterone concentrations was detected by 9 days following treatment. Within 12 hr following PGF2α in Group IV, progesterone concentrations had declined (P<.05) from 1.5 ng/ml to .6 ng/ml and the cystic structure was not detected at the subsequent estrus or silent estrus. Positive responses for cows in Group III were variable and not easily discernible. In summary, data in this study indicate that the luteinized ovarian cyst is responsive to the luteolytic effects of PGF2α and PGF2α 9 days following GnRH appeared to be the most desirable treatment for ovarian cysts.