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Development of a novel strategy for synchronization of ovulation and fertility augmentation in cycling buffalo cows
The aim of present study was to investigate the endocrine changes (progesterone, total estrogens, and LH), ovarian follicular growth, timing of ovulation and efficacy in terms of pregnancy rate in cycling Murrah buffaloes subjected to a novel protocol named Estradoublesynch (PGF2α 0, GnRH 2, PGF2α 9, Estradiol Benzoate; EB 10, timed artificial insemination (TAI) 48 and 60 h later). Twelve cycling buffaloes were subjected to the Estradoublesynch protocol. Ovarian follicle size and the rate of induction of ovulation were examined using transrectal ultrasonography at 2 hourly intervals post EB injection. Plasma progesterone and total estrogens concentrations were measured in blood samples collected at daily intervals. In addition, plasma LH and total estrogens concentrations were determined in intensive blood samples collected post EB administration. Ovulation occurred in all buffaloes 48.5±1.6 h post EB treatment. Follicle size was gradually increased from second PGF2α injection (9.7±0.3 mm) until ovulation (12.9±0.4 mm). Peak LH concentration of 34.2±7.7 ng/ml occurred 18.3±0.8 h after EB treatment. Peak total estrogen of 50.8±6.9 pg/ml occurred 5.7±1.0 h after EB treatment. Fourteen cycling buffaloes were subjected to the Estradoublesynch protocol, with TAI 48 and 60 h following EB injection, and 58 cycling buffaloes were inseminated after spontaneous estrus (control group). Pregnancy rates were 62% for TAI of cycling buffaloes and 34.5% for control group. These results demonstrated that the Estradoublesynch protocols can be potentially used to obtained satisfactory fertility after TAI in cycling buffaloes. This is a practical application of endocrine study toward fertility augmentation at farm level.
Keywords: Estradoublesynch; Ovulation, Ovarian follicle