Pregnancy Rate in Lactating Buffaloes Treated with or without Estradiol after Estrus Synchronization Protocols at Timed AI

The present study was conducted to compare the reproductive performance of forty lactating Nili-Ravi buffalos treated with GnRH and PGF2 alpha for synchronization of estrus and ovulation with or without supplemental Estradiol. At Buffalo Research Institute, Pattoki, District Kasur, forty buffaloes received 25 mg PGF2 alpha at 51 day post-partum for pre-synchronization of estrus cycles. After 13 days of PGF2 alpha injection, buffaloes were given one of 4 treatments; Group A were given an intramuscular injection of 100 mu g of GnRH followed by an injection of PGF2 alpha 7 days later and a final injection of GnRH at timed artificial insemination (AI) 48 hour after PGF2 alpha (OvSynch48) whereas Group B were given same treatment as given to group A buffaloes but with an injection of 1 mg of Estradiol 24 hour after PGF2 alpha injection. Group C (n=10) were given an intramuscular injection of 100 mu g of GnRH followed by an injection of PGF2 alpha 7 days later and a final injection of GnRH at timed artificial insemination (AI) 72 hour after PGF2 alpha (OvSynch72) whereas Group D were given same treatment as given to group C buffaloes but with an injection of 1 mg of Estradiol 24 hour after PGF2 alpha injection. The estrus expression was 30 %, 60 %, 50 %, 80 % in group A, B, C and D. There was significant difference (P < 0.05) in estrus expression between all groups. At day 40 and 68, 40 %, 50 %, 50 %, 40 % animals were detected pregnant in group A, B, C, D, respectively. There was significant difference (P < 0.05) between group A and B, C, whereas non-significant difference (P > 0.05) between group A, D and group B, C, respectively. There was non-significant difference (P > 0.05) in serum progesterone concentrations between group A, B, C, D, buffaloes at 7 days before, at the first GnRH, at final GnRH and 7 days after GnRH of the OvSynch protocols, respectively. It was concluded, that in buffaloes, extending the period of proestrus and supplementing with estradiol increased display of estrus primarily at 72 hours after PGF2 alpha but did not improve fertility.