Full Length Research Paper

Follicular and ovulatory responses of the right versus left ovaries to eCG treatment in Shall Iranian ewes

Hamed Kermani Moakhar¹, Hamid Kohram^1,2*, Reza Salehi¹ and Ahmad Zare Shahneh¹

¹Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.

²Depertment of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University, Ahvaz, Iran.

*Corresponding author. E-mail: kohram@can.ut.ac.ir. Tel: +98-261-2248082. Fax: +98-261-2246752.

Abbreviations: eCG, Equine chorionic gonadotrophin; LF, large follicle; CL, corpus luteum; FSH, follicle stimulating hormone; CIDR, progesterone-releasing intravaginal device.

Accepted 11 February, 2010

   Abstract

The present study considers the right versus the left ovarian responses to the different doses of eCG treatment in ewe. The estrous cycles of 32 adult Shall Iranian ewes were synchronized by CIDR during breeding period. At the time of CIDR removal, 0 (n = 8), 450 (n = 8), 550 (n = 8) and 650 (n = 8) IU of eCG (Intervet, Booxmer, Netherlands) was administered to ewes. The number of large follicles (> 3 mm, LF) and CL in the right and left ovaries was monitored by transrectal ultrasonography on the day of estrus and 6 days later. In another analysing view, all ewes (n = 32) were set into 3 groups. Following superovulation, groups A and D ewes had at least one extra large follicle and CL, respectively, in their right ovary than that of the left one. Group B and E had the opposite position and group C and F had equal LF in their ovaries. The data were analysed by GLM procedure of SAS. The mean number of LF in the right (2.35 ± 0.14) was higher (P < 0.001) in comparison to the left (1.42 ± 0.14) ovaries in all treatment groups. Also, the mean number of LF in the right was higher (P < 0.05) than that in the left ovaries between every treatment group. In addition, the mean number of CL in the right (1.92 ± 0.47) was higher (P < 0.05) in comparison to the left (1.33 ± 0.25) ovaries in all treatment groups. Furthermore, in the other analysis, we observed 62.5% of the ewes were in group A (n = 20) which was a higher (P < 0.001) percentage compared to group B (n = 4, 12.5%) and group C (n = 8, 25%). Also, it is observed that 44% of the ewes were set into group D (n = 16) (the right ovary had at least one CL extra in comparison with the left ovary) which was a higher (P < 0.05) percentage compared to groups E and F; and that both groups had equal number of ewes. The results suggest that the greater responses of follicular development occur in the right ovaries after eCG treatment in Shall Iranian ewes.

Key words: Ewe, Shall, follicle, CIDR, eCG.