Oestrus synchronization may be used to overcome poor oestrus expression and seasonality of breeding in buffalo (Bubalus bubalis). The present work was conducted to compare the efficiency of an oestrus synchronization protocol “ovsynch” in Nili Ravi buffalo during peak (n=8) and low breeding seasons (n=11) by determining luteinizing hormone (LH) peak and progesterone (P4) rise in blood plasma using ELISA. Buffaloes were administered gonadotropin releasing hormone (GnRH) analogue (50 µg lecirelin; day 0) followed by prostaglandinF2α (PGF2α) analogue (150 µg cloprostenol; day 7) and again GnRH analogue at 36 hours after PGF2α. Blood sampling for LH was started 12 h after PGF2α injection and done at 3 h interval up to 108 h. An animal was considered to have responded to ovsynch protocol if it showed LH peak within 48 h after PGF2α injection (and within 3-6 h after second GnRH injection)” and showed a P4 concentration of >2.0 ng/ml on day 18 after the 1st GnRH injection. 87.5% animals showed positive response to ovsynch protocol in term of oestrus and ovulation synchronization during the peak season as assessed by LH peak and P4 level while only 36.36 % animals responded to synchronization treatment during low breeding season (P<0.05). The LH peak in responsive animals was 11.48±1.98 and 10.38±1.77 ng/ml in peak and low breeding season respectively. It is concluded that Ovsynch protocol in buffaloes resulted in a significantly better response during peak breeding season as compared to that in low breeding season.

Key words: Buffalo, LH, Oestrus synchronization, Progesterone, Season