Administration of a luteolytic dose of PGF2α at the time of AI.

The aim of this study was to verify if the administration of a luteolytic dose of PGF2α at the time of AI is able to anticipate ovulation and, hence, to increase fertility rate. Furthermore, the presence of a “farm effect” was also evaluated. The trial was performed in two commercial farms (A and B) located in Caserta on 584 buffaloes (Farm A: n=389; Farm B: n=195), synchronized by the Ovsynch-TAI Program. In each farm buffaloes were divided in two groups: treated group (n=181 and n=95, respectively in farms A and B) received an intramuscular injection of 0.524 mg cloprostenol (Estrumate®, Schering-Plough Animal health, S.p.A., Milan, Italy) at the time of AI while control group (n=208 and n=100) received an intramuscular injection of physiologic saline (0.9% NaCl). No differences were present with regard to the number of AI/subject, in terms of pregnancy rate and ovulation rate between treated and control groups. It is worth pointing out that the control group in farm A showed a higher (P<0.01) conception rate compared to the control group in farm B (46.15 vs. 30.00). Furthermore, within farm B buffaloes treated by cloprostenol on the day of AI showed higher (P<0.01) pregnancy rate vs. animals that received saline (51.58% vs. 30.00%). These results suggest that if fertility in control group is high, treatment by cloprostenol does not affect pregnancy rate and ovulation rate.