Effect of oestradiol benzoate on oestrus intensity and pregnancy rate in CIDR treated anoestrus nulliparous and multiparous buffalo

The objective of the present study was to examine if administration of oestradiol benzoate (OEB) after removal of control internal drug releasing device (CIDR) could enhance oestrous intensity and pregnancy rate in anovular nulliparous and multiparous Nili-Ravi buffalo. For this, a total of 298 nulliparous (n = 91) and multiparous (n = 207) buffaloes received a CIDR on Day 0, and were administered PGF2α on Day 6 followed by removal of CIDR on Day 7. At Day 8, OEB was administered in approximately half of nulliparous (n = 45/91) and multiparous (n = 100/207) buffalo. All animals were fixed time inseminated 48 and 60 h after CIDR removal, respectively. The results showed that administration of OEB but not the parity, improved oestrous intensity (3.15 ± 0.05 vs 2.99 ± 0.05; P = 0.0026) compared to those not received OEB, respectively. However, OEB did not affect (46.2 vs 44.1; P = 0.8) pregnancy per AI (P/AI). In addition, P/AI was greater (50.7 vs 39.6; P = 0.036) in multiparous compared to nulliparous buffalo, respectively. The oestrous intensity (P = 0.025) and response to OEB (P = 0.0002) was greater in buffalo having a greater body condition (>3.0). Though, non significant, timing of ovulation was more synchronous (62.9 ± 1.8 vs 72.4 ± 3.6 h; P > 0.05) and ovulation rate was greater (91% vs 64%; P > 0.05) in buffalo after OEB administration. It is concluded that administration of OEB in conjunction with the CIDR improves oestrous intensity without affecting P/AI in nulliparous and multiparous anovular buffalo.