Resynchronization with Ovsynch Improves Cumulative Pregnancy and Reduces Embryonic Losses in CIDR-GnRH Synchronized Nili-Ravi Buffalo

The objective of the present study was to determine the effect of resynchronization on Day 23 either with OVS or CIDR on pregnancy rate, cumulative pregnancy, embryonic and fetal losses in CIDR-GnRH synchronized Nili-Ravi buffalo. For this, buffalo of mixed parity (n = 181), lactating, 181 ± 72.8 days postpartum, having BCS 3.2 ± 0.5 (scale of 1-5) and 400-600 kg weight were subjected to the synchronization as well as resynchronization. All buffalo received CIDR protocol on Day -9.5. In addition, GnRH was injected 36 h after CIDR removal and FTAI was performed 18 h later (Day 0). On Day 23, buffalo were randomly assigned to receive one of the following treatments 1) OVS (n=63), 2) CIDR (n=55) and 3) control (CON; n=63) for resynchronization (2^nd AI). Pregnancy rate and embryonic and fetal losses were monitored by serial ultrasonography on Day 30, 45, 60 and 90 after synchronization (1^st AI), respectively. The pregnancy retention rate in OVS buffalo remained significantly and consistently higher (P < 0.05) than the CON at day 30, 45, 60 and 90 after 1^st FTAI. The pregnancy rate in resynchronized open buffalo did not differ (P > 0.05) between OVS and CIDR groups. Whereas, cumulative pregnancy rate in OVS group (84%) after first and second FTAI when determined on Day 64 was higher (P < 0.05) than CON (59%) group. The embryonic losses were significantly lower (P < 0.05) in OVS (18%) buffalo, when compared to CON (42%) buffalo on Day 45 post 1^st AI. Fetal losses were fewer and did not differ (P > 0.05) due to treatment on Day 60 or 90 post 1^st AI. In conclusion, i) the pregnancy rate and cumulative pregnancy rate in OVS buffalo was higher than CON buffalo when determined on Day 64 after resynchronization, ii) embryonic and fetal losses were lower in OVS buffalo when determined from Day 31 - 90 compared to CON buffalo.