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Comparison of endocrine changes, timing of ovulations, ovarian follicular growth, and efficacy associated with Estradoublesynch and Heatsynch protocols in Murrah buffaloes (Bubalus bubalis)
Experiments were conducted on 135 cycling and 31 anestrus buffalos to compare a) the endocrine changes, timing of ovulations, ovarian follicular growth and efficacy of Estradoublesynch (PGF2α 0, GnRH 2, PGF2α 9, Estradiol Benzoate; EB 10) and Heatsynch (GnRH 0, PGF2α 7, EB 8) protocols in cycling buffaloes, and b) the efficacy of Estradoublesynch and Heatsynch protocols for fertility improvement in cycling and anestrus buffaloes. Ovulation was confirmed following all GnRH and EB treatments by ultrasonographic examination at 2-h intervals. Plasma progesterone and total estrogen concentrations were determined in blood samples collected at daily intervals, beginning 2 days before onset of protocols until the day of second ovulation detection. Ovulatory follicle size was measured at the time of a) first PGF2α administration/2days before onset of protocol, b) GnRH administration, c) 2 h before ovulation detection post GnRH administration, d) second PGF2α/PGF2α injection, e) EB injection and, f) 2 h before ovulation detection post EB injection. Plasma LH, total estrogen and progesterone concentrations were determined in blood samples collected at 30-min intervals for 8 h, beginning GnRH and EB injections, and thereafter at 2-h intervals until 2 h after detection of ovulation. The first ovulatory rate was significantly (P<0.05) higher in Estradoublesynch (84.6%) protocol than that in Heatsynch protocol (36.4%). The first LH Peak concentration in Estradoublesynch (74.6±10.4 ng/ml) protocol was significantly (P<0.05) higher than that of Heatsynch (55.3±7.4 ng/ml) protocol. In Estradoublesynch protocol, the total estrogen concentration gradually increased from the day of GnRH administration coinciding with LH peak, and then gradually declined to the basal level until the time of ovulation detection. However, in Heatsynch protocol, the gradual increase in total estrogen concentration after GnRH was observed only in those buffaloes which responded to treatment with ovulation. In both Estradoublesynch and Heatsynch protocols, ovulatory follicles size increased from GnRH/EB injections until ovulation. The pregnancy rate after Estradoublesynch (60.0%) protocol was significantly (P<0.05) higher than that achieved after Heatsynch protocol (32.5%). Satisfactory success rate using Estradoublesynch protocols was attributed to the higher release of LH following GnRH injection, leading to most of the animals ovulating post GnRH injection and hence creating the optimum follicular size at EB injection for ovulation and pregnancy to occur.
Keywords: Estradoublesynch; Heatsynch, Endocrine Changes