EFFECTIVENESS OF PROSTAGLANDIN-F2-ALPHA IN THE INITIAL TREATMENT OF BOVINE OVARIAN CYSTS

This study was conducted to evaluate the use of prostaglandin F2alpha (PGF2alpha) in the initial treatment of ovarian cysts in dairy cattle. Two hundred and sixty three cows diagnosed cystic on palpation per re ctum were randomly assigned to one of three treatment groups (A, B or C). Cows in Groups A and B were treated with 25 mg i.m.of PGF2alpha at the time of diagnosis (Day 0), while cows in Group C received 100 mug of GnRH. Seven days following initial treatment (Day 7), cows from Gr oup A that were not observed in estrus were treated with GnRH. Cows fr om Groups B and C were not treated. On Day 14, all cows that had not b een inseminated received PGF2alpha. A blood sample was obtained from a ll cows on Days 0, 7 and 14 and was analyzed for progesterone (P4) usi ng radioimmunoassay. Incidences of estrus were recorded and cows that were more than 60 d in milk at the time of diagnosis were bred when ob served in estrus. The incidence of follicular cysts on Day 0 (as defin ed as P4 <0.5 ng/ml) was similar between groups and constituted about 40% of all cysts. There were significantly more cows pregnant to insem ination within 7 d of initial treatment in Group B than in Groups A an d C (P<0.05). After Day 14, the pregnancy rate was not statistically d ifferent between Group B and C, but Groups B and C had a statistically higher pregnancy rate than Group A from Day 21 to Day 35. At the end of the study, there was no statistical difference for the pregnancy ra te between groups. We concluded that treatment of ovarian cysts diagno sed by per rectum examination with prostaglandin (at time of diagnosis and 14 d later for cows that were not inseminated) was as effective a s initial treatment with GnRH followed by prostaglandins 14 d later fo r cows that were not inseminated previously. Cows that were initially treated with prostaglandins also tended to become pregnant sooner.