Half dose of prostaglandin F2a is effective to induce luteolysis in the synchronization of ovulation protocol for fixed-time artificial insemination in buffalo (Bubalus bubalis)

Abstract

The objective of this study was to evaluate the efficiency of half dose of PGF2alpha in the synchronization of ovulation protocol (GnRH/PGF2alpha/GnRH) for fixed-time artificial insemination in buffalo. Two hundred and sixty two buffaloes (³40 days postpartum) were divided in 2 groups (Group 1, n = 125, GnRH/ ½ dose de PGF2alpha/GnRH; Control Group, n = 137, GnRH/PGF2alpha/GnRH). Animals in Group 1 received 25mg of GnRH IM (Lecirelin, Gestran-plus®) and, seven days later, half dose of PGF2alpha IM (75mg d-cloprostenol, Preloban®). Two days after PGF2alpha injection, all animals received 25mg of GnRH IM (Lecirelin). Animals in Control Group received the same treatment, except for the dose of PGF2alpha(150mg, IM, d-cloprostenol, Preloban®). All animals were fixed-time inseminated 16 hours after the second GnRH injection. Blood samples were collected from 35 buffaloes in Group 1 and 30 buffaloes in Control Group on day of PGF2alpha and second GnRH injections to measure plasma progesterone concentrations. Conception rate was not influenced by PGF2alpha dosage (P>;0.05). Conception rates were 48.00% (60/125) and 40.90% (56/137) in Group 1 and Control Group, respectively. It was observed that 88.60% (n = 35) of the buffaloes in Group 1 and 90.00% (n = 30) in Control Group presented luteolysis 48 hours after the PGF2alpha injection (P>;0.05). In summary, present data show that both treatments result in acceptable conception rates. Therefore, the recommended dose of PGF2alpha can be reduced in 50.00% in the synchronization of ovulation protocol for fixed-time artificial insemination in buffalo.