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Online Journal of Veterinary Research©
Volume 16(1):26-37, 2012
Ovarian response to Ovsynch in presence or absence of dominant follicle in heifers
Kafi M, Chalmeh AA, Mirzaei A.
Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Kafi M, Chalmeh AA, Mirzaei A., Ovarian response to Ovsynch in presence or absence of dominant follicle in heifers, Online J Vet Res, 16(1):26-37, 2012. Growth of ovarian follicle and corpus luteum during estrus was evaluated in groups of 6 Holstein cross heifers using transrectal ovarian ultrasonography and serum progesterone (P4) as control. A group started Ovsynch at day 7 of estrus with dominant follicle and another started but in absence of a dominant follicle on day 10 of estrus. Ovsynch was initiated with gonadotropin-releasing hormone agonist followed 7 days later with prostaglandin F2α. Heifers received a second gonadotropin-releasing hormone agonist 36 h after prostaglandin F2α injection. Transrectal ovarian ultrasonography was carried out daily to determine the growth of the ovarian follicles, the development of the corpus luteum and the occurrence of ovulation throughout the oestrous cycle of the heifers in both groups. Blood samples were also collected before each session of scanning every other day. The results showed that the application of Ovsynch protocol may result in various abnormalities in ovarian functions including the incomplete luteolysis of the corpus luteum, abnormalities in oestrus characteristics, and disturbances in the corpus luteum development in post-synchronisation period in Holstein × local Sistani heifers.
Key words: Ovarian responses; Ovsynch protocol; Dominant follicle; Heifers; Cattle.