The effects of three methods of synchronization on estrus induction and hormonal profile in Kalkuhi ewes: A comparison study

Abstract

Due to the importances of estrus synchronization in sheep reproduction and fertility, the present trial had been carried out to compare the three methods of estrus synchronization in ewes during breeding season. 60 cycling, fat-tailed Iranian Kalkuhi ewes were randomly allocated in equal numbers (n = 20) to 3 treatment groups. In two treatment groups, sponges (medroxyprogesterone) and controlled intravaginal drug-releasing devices (CIDR) were inserted for a period of 14 and 12 days respectively; also, another group received two injections of prostaglandin F2alpha (PGF2α) (with 11 days interval). At the time of CIDR/sponge removal and second PGF2α administration, all the animals received 400 IU of pregnant mare serum gonadotropin (PMSG). Blood samples were collected from all of the treated ewes, and progesterone (P4) and estradiol (E2) concentrations were measured by double-antibody enzyme immune-assay (ELA). Estrus synchronization by CIDR was as effective as Sponge and PGF2α treatments; also CIDR treated ewes exhibited overt signs of estrus earlier than those in other treatment groups. Following hormonal assays, P4 concentrations at first and second sampling and estradiol concentrations at second and third sampling were significantly different (P < 0.05).

Key words: Ewe, reproduction, synchronization, estradiol, progesterone.