Endocrine changes, timing of ovulation, ovarian follicular growth and efficacy of a novel protocol (Estradoublesynch) for synchronization of ovulation and timed artificial insemination in Murrah buffaloes (Bubalus bubalis)

Abstract

Experiments were conducted to investigate (1) ovarian follicular growth, timing of ovulation and associated endocrine changes (progesterone, estrogen, and LH) in cycling, and (2) efficacy in terms of pregnancy rate in cycling and anestrus Murrah buffaloes subjected to the Estradoublesynch protocol (prostaglandin F2α [PGF2α] 0, GnRH 2, PGF2α 9, estradiol benzoate, EB 10). Twelve cycling buffaloes were subjected to the Estradoublesynch protocol and observed for ovulation, follicle size, and endocrine changes after EB treatment. Ovulation occurred in 12 of 12 buffaloes (100%) at 48.5 ± 1.6 hours (range, 38.0–56.0) after EB treatment. Plasma LH, total estrogen, and progesterone concentrations were determined in intensive blood samples collected after EB treatment. Peak LH concentration of 34.2 ± 7.7 ng/mL (range, 17.8–178.5) occurred at 18.3 ± 0.8 hours (range, 14.0–22.0) after EB treatment. Peak total estrogen of 50.8 ± 6.9 pg/mL (range, 32.3–82.7) occurred 5.7 ± 1.0 hours (range, 2.0–14.0) after EB treatment. Follicle size was gradually increased from second PGF2α injection (9.7 ± 0.3 mm; range, 8.0–12.0) until ovulation was detected (12.9 ± 0.4 mm; range, 11.0–15.0). Fourteen cycling and 11 anestrus buffaloes were subjected to the Estradoublesynch protocol, with timed artificial insemination (TAI) 48 and 60 hours after EB treatment, and 58 cycling buffaloes were inseminated after spontaneous estrus (control group). Pregnancy rates were 62% for TAI of cycling buffaloes, 64% for anestrus buffaloes, and 34.5% for control group. Our observations demonstrated that the Estradoublesynch protocol followed by TAI satisfactory enhanced pregnancy rates in both cycling and anestrus buffaloes.