This study was conducted to evaluate the efficacy of reducing GnRH dose on the formation of ovulation and conception, and sizes of the ovarian structures following an Ovsynch program in lactating cows. The cows were allocated randomly to two treatment groups (full dose; FD, n=20 and half dose; HD, n=20). Cows in the FD group were treated with 10.5 µg buserelin acetate on day 0, with 0.150 mg D- cloprostenol 7 d later and with 10.5 µg buserelin acetate 2 d later. Estrous cycles in HD group were synchronized using the same scheme as FD-treated cows, but the dose of buserelin acetate was reduced to 5.25 µg at both GnRH administration times. Ovarian structures were monitored by ultrasound with a 6-8 MHz linear trans-rectal probe on days 0, 7, 9, 10, and 11. Cows were inseminated at the 16-20 h after second GnRH administration. No significant differences were observed in the dominant or ovulatory follicle diameters in FD and HD groups. Ovulation incidence from second GnRH injection by the 24 hour after fixed-time AI did not differ between FD (85 %) and HD (90 %) groups. Also, the conception percentages did not differ statistically between the HD (50%) and FD (40 %) groups.
Contribution/ Originality
This study is one of very few studies which have investigated the effect of reducing doses of buserelin acetate on the follicular development, ovulation and conception rates in the Ovsynch program of dairy cows.
W. W. Thatcher, T. R. Bilby, J. A. Bartolome, F. Silvestre, C. R. Staples, and J. E. P. Santos, "Strategies for improving fertility in the modern dairy cow," Theriogenology, vol. 65, pp. 30-44, 2006. View at Google Scholar | View at Publisher
C. S. Whisnant, S. P. Washburn, and P. W. Farin, "Current concepts in synchronization of estrus and ovulation of dairy cows," Journal of Animal Science, vol. 77, pp. 1-8, 2000. View at Google Scholar | View at Publisher
M. C. Lucy, S. McDougall, and D. P. Nation, "The use of hormonal treatments to improve the reproductive performance of lactating dairy cows in feedlot or pasture-based management systems," Animal Reproduction Science, vol. 82–83, pp. 495-512, 2004. View at Google Scholar | View at Publisher
J. R. Pursley, M. O. Mee, and M. C. Wiltbank, "Synchronization of ovulation in dairy cows using PGF2a and GnRH," Theriogenology, vol. 44, pp. 915-923, 1995. View at Google Scholar | View at Publisher
J. R. Pursley, M. C. Wiltbank, J. S. Stevenson, J. S. Ottobre, H. A. Garverick, and L. L. Anderson, "Pregnancy rates per artificial insemination for cows and heifers inseminated at a synchronized ovulation or synchronized estrous," Journal of Dairy Science, vol. 80, pp. 295- 300, 1997. View at Google Scholar | View at Publisher
J. R. Pursley, R. W. Silcox, and M. C. Wiltbank, "Effect of time of artificial insemination on pregnancy rates, calving rates, pregnancy loss, and gender ratio after synchronization of ovulation in lactating dairy cows," Journal of Dairy Science, vol. 81, pp. 2139-2144, 1998. View at Google Scholar | View at Publisher
S. Suadsong, "Control of oestrus and ovulation in cows," Thai Journal of Veterinary Medicine Supplement, vol. 41, pp. 95-98, 2011. View at Google Scholar
A. R. Rabiee, I. J. Lean, and M. A. Stevenson, "Efficacy of ovsynch program on reproductive performance in dairy cattle: A meta-analysis," Journal of Dairy Science, vol. 88, pp. 2754-2770, 2005.View at Google Scholar | View at Publisher
P. M. Fricke, J. N. Guenther, and M. C. Wiltbank, "Effıcacy of decreasing the dose of GnRH used in a protocol for synchronization of ovulation and timed AI in lactatıng dairy cows," Theriogenology, vol. 50, pp. 1275-1284, 1998.View at Google Scholar | View at Publisher
K. Yamada, T. Nakao, K. Nakada, and G. Matsuda, "Influence of GnRH analogue (fertirelin acetate) doses on synchronization of ovulation and fixed-time artificial insemination in lactating dairy cows," Animal Reproduction Science, vol. 74, pp. 27-34, 2002.View at Google Scholar | View at Publisher
A. Ahmadzadeh, R. Manzo, C. B. Sellars, and J. C. Dalton, "The efficacy of a reduced dose of gonadotropin releasing hormone on the time and incidence of ovulation in Holstein cows," Journal of Animal and Veterinary Advances, vol. 6, pp. 1328-1332, 2007. View at Google Scholar
J. R. Chenault, "Effect of fertirelin acetate or buserelin on conception rate at first or second insemination in lactating dairy cows," Journal of Dairy Science, vol. 73, pp. 633-638, 1990.View at Google Scholar | View at Publisher
K. L. Macmillan, B. V. E. Segwagve, and C. S. Pino, "Associated between the manipulation of patterns of follicular development and fertility in cattle," Animal Reproduction Science, vol. 78, pp. 327-344, 2003.View at Google Scholar | View at Publisher
H. Twagiramungu, L. A. Guilbault, and J. J. Dufour, "Synchronization of ovarian follicular waves with a gonadotropin-releasing hormone agonist to increase the precision of estrous in cattle: A review," Journal of Animal Science, vol. 73, pp. 3141-3151, 1995. View at Google Scholar | View at Publisher
Z. Z. Xu, L. J. Burton, and K. L. Macmillan, "Reproductive performance of lactating dairy cows following estrous synchronization regimens with PGF2α and progesterone," Theriogenology, vol. 47, pp. 687-701, 1997.View at Google Scholar | View at Publisher
M. M. Herlihy, M. A. Crowe, M. G. Diskin, and S. T. Butler, "Effects of synchronization treatments on ovarian follicular dynamics, corpus luteum growth, and circulating steroid hormone concentrations in lactating dairy cows," Journal of Dairy Science, vol. 95, pp. 743-754, 2012.View at Google Scholar | View at Publisher
C. Taylor and R. Rajamahendran, "Follicular dynamics and corpus luteum growth and function in pregnant versus nonpregnant dairy cows," Journal of Dairy Science, vol. 74, pp. 115-123, 1991. View at Google Scholar | View at Publisher
M. C. Veronesi, G. Gabai, M. Battocchio, A. Mollo, F. Soldano, G. Bono, and F. Cairoli, "Ultrasonographic appearance of tissue is a better indicator of CL function than CL diameter measurement in dairy cows," Theriogenology, vol. 58, pp. 61-68, 2002. View at Google Scholar | View at Publisher
A. Gümen, J. N. Guenther, and M. C. Wiltbank, "Follicular size and response to ovsynch versus detection of estrus in anovular and ovular lactating dairy cows," Journal of Dairy Science, vol. 86, pp. 3184-3194, 2003. View at Google Scholar | View at Publisher
P. M. Fricke, "Scanning the future-ultrasonography as a reproductive management tool for dairy cattle," Journal of Dairy Science, vol. 85, pp. 1918-1926, 2002. View at Google Scholar | View at Publisher
R. C. Bicalho, K. N. Galvão, C. L. Guard, and J. E. P. Santos, "Optimizing the accuracy of detecting a functional corpus luteum in dairy cows," Theriogenology, vol. 70, pp. 199-207, 2008. View at Google Scholar | View at Publisher
H. Kaneko, T. Terada, K. Taya, G. Watanabe, S. Sasamoto, Y. Hasegawa, and M. Igarashi, "Ovarian follicular dynamics and concentrations of oestradiol-17 beta, progesterone, luteinizing hormone and follicle stimulating hormone during the periovulatory phase of the oestrous cycle in the cow," Reproduction, Fertility and Development, vol. 3, pp. 529-535, 1991.View at Google Scholar | View at Publisher
B. Bülbül, M. Kırbaş, M. Köse, Ş. Dursun, and M. Çolak, "The affects of ovsynch started in different phases of oestrus cycle on oestrus synchronization in cows," Journal of the Faculty of Veterinary Medicine, vol. 35, pp. 7-17, 2009. View at Google Scholar
D. Cavestany, A. Meikle, H. Kindahl, E. Van Lier, F. Moreira , W. W. Thatcher, and M. Forsberg, "Use of medroxyprogesterone asetate (MAP) in lactating Holstein cows within an ovsynch protocol: Follicular growth and hormonal patterns," Theriogenology, vol. 59, pp. 1787-1798, 2003. View at Google Scholar | View at Publisher
N. M. Bello, J. P. Steibel, and J. R. Pursley, "Optimizing ovulation to first GnRH improved outcomes to each hormonal injection of ovsynch in lactating dairy cows," Journal of Dairy Science, vol. 89, pp. 3413-3424, 2006. View at Google Scholar | View at Publisher
J. L. M. Vasconcelos, R. W. Silcox, G. J. M. Rosa, J. R. Pursley, and M. C. Wiltbank, "Synchronization rate, size of the ovulatory follicle, and pregnancy rate after synchronization of ovulation beginning on different days of the estrous cycle in lactating dairy cows," Theriogenology, vol. 52, pp. 1067-1078, 1999. View at Google Scholar | View at Publisher
R. L. A. Cerri, H. M. Rutigliano, R. C. Chebel, and J. E. P. Santos, "Period of dominance of the ovulatory follicle influences embryo quality in lactating dairy cows," Reproduction, vol. 137, pp. 813-823, 2009.View at Google Scholar | View at Publisher
J. E. P. Santos, C. D. Narciso, F. Rivera, W. W. Thatcher, and R. C. Chebel, "Effect of reducing the period of follicle dominance in a timed artificial insemination protocol on reproduction of dairy cows," Journal of Dairy Science, vol. 93, pp. 2976-2988, 2010.View at Google Scholar | View at Publisher
M. Köse, M. Kırbaş, B. Bülbül, and A. Oyar, "Investigation of efficacy of human chorionic gonadotropin (hCG) instead of second gonadotropin-releasing hormon injection (GnRH) at ovsynch protocol in cows," Journal of the Faculty of Veterinary Medicine, Istanbul University, vol. 40, pp. 155-161, 2014.
N. Picard-Hagen, G. Lhermie, S. Florentin, D. Merle , P. Frein, and V. Gayrard, "Effect of gonadorelin, lecirelin, and buserelin on LH surge, ovulation, and progesterone in cattle," Theriogenology, vol. 84, pp. 177-183, 2015. View at Google Scholar | View at Publisher
M. C. Cordoba and P. M. Fricke, "Evaluation of two hormonal protocols for synchronization of ovulation and timed artificial ınsemination in dairy cows managed in grazing-based dairies," Journal of Dairy Science, vol. 84, pp. 2700-2708, 2001. View at Google Scholar | View at Publisher
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Funding:
This study received no specific financial support.
Competing Interests:
The authors declare that they have no competing interests.
Acknowledgement:
All authors contributed equally to the conception and design of the study.