M. Irfan-ur-Rehman Khan, M. A. Rana and N. Ahmad

Department of Theriogenology, University of Veterinary and Animal Sciences, Lahore, Pakistan 

Abstract 

    In the first experiment, effect of GnRH  and PGF_2α given intramuscularly, 9 days apart, was observed on induction of ovulation and synchronization of oestrus in anoestrous buffaloes during summer (n=2). Ovarian follicles and corpora lutea were monitored on every other day basis, using B-mode real time, transrectal ultrasonography. Oestrus detection was carried out twice daily. The diameter of the largest follicle on the day of administration of GnRH averaged 9 ± 0 mm. These follicles ovulated within 48 h after injection of GnRH. Interval to oestrus after injection of PGF_2α was 63 ± 11 h. In the second experiment, effect of follicle stimulating hormone (FSH-p) on follicular development in buffaloes during summer (n=2) was observed. FSH-p (total of 40 mg) was administered intramuscularly in divided doses, twice daily on Days 10, 11, 12 and 13. PGF_2α (2 ml) was injected on Day 13. Ovarian follicles and corpora lutea were monitored on daily basis using real time, transrectal ultrasonography. Oestrus detection was carried out twice daily. Superovulatory response was measured and analyzed by comparing follicular development on Day 10, i. e. beginning of FSH-p treatment, (before) and on Day of next oestrus (after). Superovulatory response was confirmed by determining number of corpora lutea on Day 7 after oestrus. Interval to oestrus after injection of PGF_2α was 37 ± 10 h. Mean number of small follicles decreased (P<0.05) ‘after’ FSH-p treatment than ‘before’. Mean number of medium and large follicles and corpora lutea increased (P<0.05) ‘after’ FSH-p treatment than ‘before’. It is concluded that protocol of GnRH-PGF_2α can induce ovulation and oestrus in buffaloes and reasonable superovulatory response to FSH-p can be achieved during summer when given during mid luteal phase.

Key words: Synchronization of oestrus, superovulation, ultrasonography, anoestrous buffaloes.