Document Type: Original Article

Authors

1 Sari Agricultural Sciences and Natural Resources University, Department of Animal Science, Sari, Iran

2 University of Tehran, College of Agricultural and Natural Resources, Department of Animal Science, Karaj, Iran

Abstract

The objective of this study was to determine the effects of two different time of GnRH injection after artificial insemination (A.I) (d 6 and d 12) on reproductive performances of Holstein cows during the warm season.  Cows randomly assigned to treatments 1) No GnRH injection (control, n = 300),2) GnRH injection at day 6 after A.I (G6, n=300) and 3) GnRH injection at day 12 after A.I (G12, n=300). Ultrasonography was used to detect pregnancy and late embryonic/fetal mortality between Days 32 and 60 after AI. Data were analyzed using Proc GLM of SAS. Results showed treatment affected the percentage of cows diagnosed pregnant at 32±1 d and 60±3 d after resynchronized AI. A greater percentage of G6 (25.0%) cows were pregnant at 32 d after resynchronized AI than control cows (19.3 %) and G12 cows (20.0 %). The risk of pregnancy loss between d 32 and 60 of gestation was affected by treatments and decreased in cows received GnRH injection after AI Compared to control cows. Percentage of cows that showed estrus at 19-24 d after AI was highest in G6 cows and lowest in control cows compared to other treatments. In summary, administration of a GnRH on Day 6 after AI improved reproductive performance in dairy cows.

Keywords

Ataman MB, Erdem H, Bulbul B, Umutlu S, Çolak M(2011). The effect of buserelin injection 12 days after insemination on selected reproductive characteristics in cows. ACTA. VET. BRNO. 80:171–177.

Beckett SD, Lean IJ (1997). Gonadotrophin-releasing hormone in postpartum dairy cattle: a meta-analysis of effects on reproductive efficiency. Anim. Reprod. Sci. 48:93–112.

Bulbul B, Kırbaş M,Köse M, Dursun Ş, Çolak M (2009). The effects of ovsynch started in different phases of oestrus cycle on oestrus synchronization in cows. İstanbul Üniv Vet FakDerg 35:7-17.

Celik HA, Aydin I, Sendag S, Dinc DA (2005). Number of follicular waves and their effect on pregnancy rate in the cow. Reprod. Domest. Anim. 40(2):87-92.

De Rensis F, Peters AR (1999). The control of follicular dynamics by PGF2α, GnRH, hCG and oestrus synchronization in cattle. Reprod. Dom. Anim. 34:49-59

Dirandeh E, Kohram H, ZareShahneh, A (2009). GnRH injection before artificial insemination (AI) alters follicle dynamics in Iranian Holstein cows. African. J. Biotech. 8 (15):3672-3676.

Diskin MG, Austin EJ, Roche JF (2002).Exogenous hormonal manipulation of ovarian activity in cattle. Dom.Anim. Endocrin. 23:211-228.

Drew SB, Peters AR (1992).The effect of treatment with a gonadotrophin releasing hormone analogue on the fertility of dairy cows. Proceedings of the 12th International Congress on Animal Reproduction, Hague, Netherlands, 319 p.

Hansen PJ (2002). Embryonic mortality in cattle from the embryo’s perspective. J. Anim. Sci. 80:33-44.

Kastelic JP (1994). Noninfectious embryonic loss in cattle. Vet. Med. 6:584-589.

Kohram H, Bousquet D, Durocher J, Guilbault LA. (1998) Alteration of follicular dynamics and superovulatory responses by gonadotropin releasing hormone and follicular puncture in cattle: a field trial. Theriogenology. 49(6):1165-74.

Lopez-Gatius F, Santolaria P, Martino A, Dele´tang F, De Rensis F(2006). The effects of GnRH treatment at the time of AI and 12 days later on reproductive performance of high producing dairy cows during the warm season in northeastern Spain. Theriogenology. 65:820–830.

Mann GE, Lamming GE, Fray MD (1995). Plasma oestradiol and progesterone during early pregnancy in the cow and the effects of treatment with Buserelin. Anim. Reprod. Sci.37:121–31.

Moreira F, De La Sota RL, Diaz T, Thatcher WW (2000).Effect of day of the estrous cycle at the initiation of a timed artificial insemination protocol on reproductive responses in dairy heifers. J. Anim. Sci. 78:1568-1576.

Peters AR, Martinez TA, Cook AJC (2000). A meta-analysis of studies of the effect of GnRH 11–14 days after insemination on pregnancy rates in cattle. Theriogenology.54:1317–26.

Rettmer I, Stevenson JS, Corah LR (1992). Endocrine responses and ovarian changes in inseminated dairy heifers after an injection of a GnRH agonist 11 to 13 days after estrous. J. Anim. Sci. 70:508-517.

Schmitt EJ, Diaz T, Barros CM, de la Sota RL, Drost M, Fredriksson EW, Staples CR, Thorner R, Thatcher WW. les CR, Thorner R, Thatcher (1996a).Differential response of the luteal phase and fertility in cattle following ovulation of the first-wave follicle with human chorionic gonadotropin or an agonist of gonadotropin-releasing hormone. J. Anim. Sci.74:1074-1083.

Schmitt EJ, Barros CM, Fields PA, Fields MJ, Diaz T, Kluge JM, Thatcher WW (1996b). A cellular and endocrine characterization of the original and induced corpus luteum after administration of a gonadotropin-releasing hormone agonist or human chorionic gonadotropin on day five of the estrous cycle. J. Anim. Sci. 74:1915-1929.

Sheldon M, Dobson H (1993). Effects of gonadotrophin releasing hormone administered 11 days after insemination on the pregnancy rates of cattle to the first and later services. Vet. Rec. 133:160-163.

Silcox RW, Powell KL, Kiser TE (1993). Ability of dominant follicles (DF) to respond to exogenous GnRH administration is dependent on their stage of development. J. Anim. Sci. 1993, Suppl. 71, 513.

Stevenson JS, Phatak AP, Rettmer IMMO, Stewart RE (1993).Post insemination administration of reeptal: follicular dynamics, duration of cycle, hormonl responses, and pregnancy rates. J. Dairy. Sci. 76:2536-2547.

Szenci O, Taka E, Sulon J,Melo de Sousa N, Beckers JF(2006). Evaluation of GnRH treatment 12 days after AI in the reproductive performance of dairy cows. Theriogenology, 66:1811–1815.

Thatcher WW, Bilby TR, Bartolome JA, Silvestre F, Staples CR, Santos JE(2006).Strategies for improving fertility in the modern dairy cow. Theriogenology. 65:30–44.

Twagiramungu H, Guilbault LA, Proulx JG, Dufour JJ (1994). Influence of corpus luteum and induced ovulation on ovarian follicular dynamics in postpartum cyclic cows treated with buserelin and cloprostenol. J. Anim. Sci. 72(7), 1796-805.

Willard S, Gandy S, Bowers S, Graves K, Elias A, Whisnant C (2003). The effects of GnRH administration post insemination on serum concentrations of progesterone and pregnancy rates in dairy cattle exposed to mild summer heat stress. Theriogenology. 59:1799-1810.