Pre-ovulatory Follicle Size, LH Peak Values and Pregnancy Induced by Three Synchronization Treatments in Buffalo Cows, during Non Breeding Season

Lactating buffalo cows (n=18) were assigned to 3 different synchronization treatments: group A (n=7) treated with PRID for 10 days + 1000 IU PMSG and PGF2 alpha (0.15mg cloprostenol) on day 7; group B (n=6) treated as group A but PMSG and PGF2 alpha were administered on day 10; group C (n=5), treated with GnRH; (150 mu g gonadorelin) on day 0 + PGF2 alpha on day 7 + GnRH on day 9 (Ovsynch protocol). Buffaloes were artificially inseminated two times (at 72 and 96h from PRID removal) in group A and B and once (at 16h from the second GnRH injection) in group C. The size of pre-ovulatory follicle was assessed by ultrasonography every 12h, starting 24h from PRID removal (group A and B) or 12h from PGF2 alpha injection (group C); at the same time blood samples were collected every 4h for the measurement of plasma LH. The pre-ovulatory follicle size was larger (P<0.05) in group A as compared to B and C groups and in ovulating as compared to non-ovulating animals (P<0.001); in animals that became pregnant the differences tended to be significant (P<0.08) as compared to non-pregnant ones. LH peak values were higher (P<0.05) in group A as compared to B and C groups and in ovulating as compared to non-ovulating animals (P<0.001). The ovulation rate (OR) was influenced by treatments: in group A it was 100%; in group B and C the ORs were 50% and 60%, respectively. The conception rates were 71, 4%, 16, 7% and 40% in group A, B and C, respectively. In conclusion the ovulation and conceptions rates were higher in animals of group A; that showed also increased pre-ovulatory follicle size and LH peak values.