Estrus and ovulation synchrony of buffaloes (Bubalus bubalis): A review

Synchronizing estrus and ovulation in buffalo using timed inseminations (TAI) protocols circumvents the limitations associated with estrus detection. Spontaneous estrus in buffalo may achieve more conception rate on insemination than those subjected to synchronization of estrus and timed insemination (TAI). The advantages of insemination following synchronization programs include higher detection rates combined with decreased embryonic losses and reduction in days open. A synchonization programme should ensure control of estrus cycle which entirely depends on ovarian status of animals before starting any protocol. Ovarian follicular status at the beginning of treatment protocols plays vital role for effective response shown by animals. Studies show that more precise alterations in follicular waves may be needed to achieve better synchrony of ovulation and more fertility. The protocols which use Gonadotropic Releasing Hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH), equine chorionic gonadotropin (eCG), human chorionic gonadotropin (hCG), prostaglandins, progesterone and estradiol have been helpful in achieving the estrus and ovulation synchrony. Use of estradiol esters and progesterone per-vaginum implants have also been incorporated in synchronization programs. Synchronous emergence of follicular waves using trans-vaginal ultrasound guided follicular ablation and estradiol administration is a recent concept for synchronization in buffalo. Further, a recent approach has been to allow the follicle of second follicular wave to ovulate as the fertility has been lesser when first wave follicle ovulates. Moreover, controlling environmental influences, nutritional and managemental strategies remain pre-requisite to achieve desired goals though hormonal administration. This is more particular in buffaloes suffering from anestrum more so in low or non-breeding season and pre-pubetal anestrum. This review will cover the available documented literature regarding estrous cycle physiology with emphasis on follicular wave dynamics and the future area of work to be focused to achieve more reproductive efficiency in buffalo.