The Effect of Administering Equine Chorionic Gonadotropins (eCG) on Reproductive Performance of Dairy Cows with a CO-Synch + CIDR Protocol and Insemination at a Fixed Time
الموضوعات :م.م. منشادی 1 , ع. رستگارنیا 2 , Sh. اسماعیلی ثانی 3
1 - Department of Clinical Science, Faculty of Veterinary Medicine, Urmia Branch, Islamic Azad University, Urmia, Iran
2 - Department of Clinical Science, Faculty of Veterinary Medicine, Urmia Branch, Islamic Azad University, Urmia, Iran
3 - Department of Clinical Science, Faculty of Veterinary Medicine, Urmia Branch, Islamic Azad University, Urmia, Iran
الکلمات المفتاحية: dairy cows, estrus synchronization, CIDR, equine chorionic gonadotropin,
ملخص المقالة :
The success of a fixed-time artificial insemination (FTAI) program depends on a high ovulation rate during a short interval. Equine chorionic gonadotropin (eCG) has been used in FTAI protocols to improve follicular growth and thereby to produce larger, more responsive follicles for ovulation with increased pregnancy rates. The aim of the present study was to evaluate the effects of eCG on conception rates of early post-partum dairy cows treated by progesterone-based estrous synchronization with artificial insemination at a fixed time (CO-Synch+CIDR protocols). 144 Holstein cows ≥ 55 days postpartum were used. All cows were enrolled in a 7-day CO-Synch + CIDR protocol which included 100 μg gonadotropin releasing hormone (GnRH) at CIDR insertion (day 0); 500 µg prostaglandin F2α (PGF2α) at CIDR removal (day 7); and 100 μg GnRH at FTAI, 66 hours after PGF2α (day 10). Cows were randomly assigned as control cows (n=69) or treated cows (n=75) which received 500 IU eCG at the time of CIDR removal. All cows were examined by ovarian ultrasound at FTAI. The addition of eCG to CO-Synch+CIDR protocols improved the frequency of estrous response (control cows 51.4%, eCG-treated cows 87.8%; P<0.01). It reduced the interval between the end of treatment and the start of estrus (control cows 56.8±5.52 hours, eCG-treated cows 45.7±5.87 hours; P<0.01). It increased dominant follicular size at FTAI (control cows 15.1±2.41 mm, eCG-treated cows 19.6±1.84 mm; P<0.001). However, eCG had no effect on pregnancy rates (control cows 49.3%, eCG-treated cows 54.6%; P=0.131). The use of eCG, prior to termination of 7-day estrus synchronization when using the CO-Synch+CIDR program alone, could hasten the time of estrous expression and should be considered in FTAI dairy cows.
Baruselli P., Reis E., Marques M., Nasser L. and Bó G. (2004). The use of hormonal treatments to improve reproductive performance of anestrous beef cattle in tropical climates. Anim. Reprod. Sci. 82, 479-486.
Bellows R. and Short R. (1972). Superovulation and multiple births in beef cattle. J. Anim. Sci. 34, 67-79.
Bó G., Baruselli P. and Mapletoft R. (2013). Synchronization techniques to increase the utilization of artificial insemination in beef and dairy cattle. Anim. Reprod. 10, 137-142.
Bryan M., Bó G., Mapletoft R. and Emslie F. (2013). The use of equine chorionic gonadotropin in the treatment of anestrous dairy cows in gonadotropin-releasing hormone/progesterone protocols of 6 or 7 days. J. Dairy Sci. 96, 122-131.
De Rensis F. and López‐Gatius F. (2014). Use of equine chorionic gonadotropin to control reproduction of the dairy cow: a review. Reprod. Domest. Anim. 49, 177-189.
De Rensis F. and Peters A.R. (1999). The control of follicular dynamics by PGF2α, gnrh, hCG and oestrus synchronization in cattle. Reprod. Domest. Anim. 34, 49-59.
Dorneles Tortorella R., Ferreira R., Tonellotto dos Santos J., Silveira de Andrade Neto O., Barreta M.H., Oliveira J.F., Gonçalves P.B. and Pereira Neves J. (2013). The effect of equine chorionic gonadotropin on follicular size, luteal volume, circulating progesterone concentrations and pregnancy rates in anestrous beef cows treated with a novel fixed-time artificial insemination protocol. Theriogenology. 79, 1204-1209.
Ferreira R.M., Ayres H., Sales J.N.S., Souza A.H., Rodrigues C.A. and Baruselli P.S. (2013). Effect of different doses of equine chorionic gonadotropin on follicular and luteal dynamics and P/AI of high-producing Holstein cows. Anim. Reprod. Sci. 140, 26-33.
Garcia-IspiertoI., Rosello M.A., De Rensis F. and Lopez-Gatius F. (2013). A five-day progesterone plus eCG-based fixed-time AI protocol improves fertility over spontaneous estrus in high-producing dairy cows under heat stress. J. Reprod. Dev. 59, 544-552.
Geary T., Whittier J., Hallford D. and MacNeil M. (2001). Calf removal improves conception rates to the Ovsynch and CO-Synch protocols. J. Anim. Sci. 79, 1-4.
Marquezini G., Mercadante V., Olson K., Jaeger J., Perry G., Stevenson J. and Lamb G. (2013). Effects of equine chorionic gonadotropin on follicle development and pregnancy rates in suckled beef cows with or without calf removal. J. Anim. Sci. 91, 1216-1224.
Meng Chao L., Sato S., Yoshida K., Kawano Y., Kojima T. and Kubota C. (2010). Comparison of oestrous intensity between natural oestrus and oestrus induced with Ovsynch based treatments in Japanese Black cows. Reprod. Domest. Anim. 45, 168-170.
Pulley S., Wallace L., Mellieon Jr H. and Stevenson J. (2013). Ovarian characteristics, serum concentrations of progesterone and estradiol, and fertility in lactating dairy cows in response to equine chorionic gonadotropin. Theriogenology. 79, 127-134.
Sá Filho M., Torres-Júnior J., Penteado L., Gimenes L., Ferreira R., Ayres H., e Paula L.C., Sales J. and Baruselli P. (2010). Equine chorionic gonadotropin improves the efficacy of a progestin-based fixed-time artificial insemination protocol in Nelore (Bos indicus) heifers. Anim. Reprod. Sci. 118, 182-187.
Sales J., Crepaldi G., Girotto R., Souza A. and Baruselli P. (2011). Fixed-time AI protocols replacing eCG with a single dose of FSH were less effective in stimulating follicular growth, ovulation, and fertility in suckled-anestrus Nelore beef cows. Anim. Reprod. Sci. 124, 12-18.
Sartori R., Fricke P.M., Ferreira J.C., Ginther O. and Wiltbank M.C. (2001). Follicular deviation and acquisition of ovulatory capacity in bovine follicles. Biol. Reprod. 65, 1403-1409.
SAS Institute. (2004). SAS®/STAT Software, Release 9.1. SAS Institute, Inc., Cary, NC. USA.
SheldonI. and Dobson H. (2000). Effect of administration of eCG to postpartum cows on folliculogenesis in the ovary ipsilateral to the previously gravid uterine horn and uterine involution. J. Reprod. Fertil. 119, 157-163.
Siqueira L., Oliveira J., Rovani M., Ferreira R., Borges L. and Gonçalves P. (2009). Effects of estradiol and progestins on follicular regression before, during and after follicular deviation in postpartum beef cows. Theriogenology. 71, 614-619.
Souza A.H., Viechnieski S., Lima F.A., Silva F.F., Araújo R., Bó G.A., Wiltbank M.C. and Baruselli P.S. (2009). Effects of equine chorionic gonadotropin and type of ovulatory stimulus in a timed-AI protocol on reproductive responses in dairy co-ws. Theriogenology. 72, 10-21.
Thatcher W., Moreira F., Santos J., Mattos R., Lopes F., Pancarci S. and Risco C. (2001). Effects of hormonal treatments on reproductive performance and embryo production. Theriogenology. 55, 75-89.
Yaniz J., Murugavel K. and López‐Gatius F. (2004). Recent de velopments in oestrous synchronization of postpartum dairy cows with and without ovarian disorders. Reprod. Domest. Anim. 39, 86-93.
