Gonadotrophin stimulation of ewes that are not pregnant following multiple matings during the season
Gonadotrophin stimulation of ewes that are not pregnant following multiple matings during the season
In this study, the aim was to obtain pregnancy following synchronization and to increase profitability in ewes that did notbecome pregnant during the breeding season after at least 3 matings. Nonpregnant Middle Anatolian Merino ewes (n = 117) were givena progesterone sponge for 9 days. At the time of sponge removal, the ewes received 250 IU pregnant mare serum gonadotropin (PMSG)+ 125 μg prostaglandin F2α (PGF2α). Two days later, they were injected with either human chorionic gonadotropin (hCG) (Group I, n =48) or gonadotropin-releasing hormone (GnRH) (Group II, n = 43), or remained as a control (Group III, n = 26). The ewes were allowedto mate at estrus following the PGF2α injection. Pregnancy diagnosis was performed on day 30 after mating by ultrasonography. Groupratios for estrus (58.3%, 55.8%, 53.8%), conception (78.6%, 87.5%, 14.3%), lambing (90.9%, 90.5%, 50.0%), multiple births (15.0%,31.6%, 0.0%), and average lamb number for birth (1.15%, 1.31%, 1.0%) were reported. In conclusion, the gonadotropin-supplementedprotocols used here were found to be useful in ewes that were not pregnant after multiple matings during the breeding season inincreasing the profitability of flocks with this problem.
___
- 1. Ali A, Derar R, Hussein H. Seasonal variation of the ovarian
follicular dynamics and luteal functions of sheep in the
subtropics. Theriogenology 2006; 66: 463-469.
- 2. Hashem NM, El-Zarkouny SZ, Taha TA, Abo-Elezz ZR.
Effect of season, month of parturition and lactation on estrus
behavior and ovarian activity in Barki Rahmani crossbred ewes
under subtropical conditions. Theriogenology 2011; 75: 1327-
1335.
- 3. Wilmut I, Sales DI, Ashworth CJ. Maternal and embryonic
factors associated with prenatal loss in mammals. J Reprod
Fertil 1986; 76: 851-864.
- 4. Noncarrow CD. Embryonic mortality in the ewe and the doe.
In: Zavy MT, Geisert RD, editors. Embryonic Mortality in
Domestic Species. Boca Raton, FL, USA: CRC Press; 1994. pp.
113-135.
- 5. Beck NFG, Davies MCG, Davies B. A comparison of ovulation
rate and late embryonic mortality in ewe lambs and ewes and
the role of late embryo loss in ewe lamb subfertility. Anim Sci
1996; 62: 79-83.
- 6. Edey TN. Embryonic mortality. In: Tomes GL, Robinson
DE, Lightfoot RJ, editors. Sheep Breeding. London, UK:
Butterworths; 1979. pp. 315-323.
- 7. Michels H, Decuypere E, Onagbesan O. Litter size, ovulation
rate and prenatal survival in relation to ewe body weight:
genetics review Small Rum Res 2000; 38: 199-209.
- 8. Quirke JF, Adams TE, Hanrahan JP. Artificial induction
of puberty in ewe lambs. In: Haresign, W, editor. Sheep
Production. London, UK; Butterworths; 1983. pp. 185-213.
- 9. Wilkins JF. Method of stimulating ovulation rate in Merino
ewes may affect conception but not embryo survival. Anim
Reprod Sci 1997; 47: 31-42.
- 10. Coleson MPT, Sanchez NS, Ashley AK, Ross TT, Ashley RL.
Human chorionic gonadotropin increases serum progesterone,
number of corpora lutea and angiogenic factors in pregnant
sheep. Reproduction 2015; 150: 43-52.
- 11. Hashem NM, El-Zarkouny SZ. Effect of short-term
supplementation with rumen-protected fat during the late
luteal phase on reproduction and metabolism of ewes. J Anim
Physiol Anim Nutr 2014; 98: 65-71.
- 12. Khan TH, Hastie PM, Beck NF, Khalid M. hCG treatment on
day of mating improves embryo viability and fertility in ewe
lambs. Anim Reprod Sci 2003; 76: 81-89.
- 13. Türk G, Gür S, Sönmez M, Bozkurt T, Aksu EH, Aksoy H.
Effect of exogenous GnRH at the time of artificial insemination
on reproductive performance of Awassi ewes synchronized
with progestagen–PMSG–PGF2a combination. Reprod Dom
Anim 2008; 43: 308-313.
- 14. Norman AW, Litwack G. Hormones. Orlando, FL, USA:
Academic Press; 1987. pp. 3-17.
- 15. Cam MA, Kuran M, Yıldız S, Erdoğan S. Fetal growth and
reproductive performance in ewes administered GnRH agonist
on day 12 post-mating. Anim Reprod Sci 2002; 72: 73-82.
- 16. Hashem NM, El-Azrak KM, Nour El-Din ANM, Taha TA,
Salem MH. Effect of GnRH treatment on ovarian activity
and reproductive performance of low-prolific Rahmani ewes.
Theriogenology 2015; 83: 192-198.
- 17. Lashari MH, Tasawar Z. The effect of GnRH given on day of
mating on ovarian function and reproductive performance in
Lohi sheep. Pakistan Vet J 2010; 30: 29-33.
- 18. Olfati A, Moghaddam GH. Effects of GnRH agonist
(CinnaRelin) on reproductive performance in synchronized
Iranian crossbred ewes during the breeding season. Slovak J
Anim Sci 2013; 46: 1-6.
- 19. Cam MA, Kuran M. Effects of a single injection of hCG or
GnRH agonist on day 12 post mating on fetal growth and
reproductive performance of sheep. Anim Reprod Sci 2004;
80: 81-90.
- 20. Inskeep EK. Preovulatory, postovulatory, and postmaternal
recognition effects of concentrations of progesterone on
embryonic survival in the cow. J Anim Sci 2004; 82: 24-39.
- 21. Khan TH, Beck NFG, Khalid M. The effects of GnRH analogue
(buserelin) or hCG (Chorulon) on day 12 of pregnancy on
ovarian function, plasma hormone concentrations, conceptus
growth and placentation in ewes and ewe lambs. Anim Reprod
Sci 2007; 102: 247-256.
- 22. Ashworth CJ, Sales DI, Wilmut I. Evidence of an association
between the survival of embryo and the periovulatory plasma
progesterone concentration in the ewes. J Reprod Fertil 1989;
87: 23-32.
- 23. Evans AC, Flynn JD, Quinn KM, Daffy P, Quinn P, Madgwick S,
Crosby TF, Bolan MP, Beard AP. Ovulation of aged follicles does
not affect embryo quality or fertility after a 14-day progestagen
estrus synchronization protocol in ewes. Theriogenology 2001;
56: 923-936.
- 24. Vinoles C, Forsberg M, Banchero G, Rubianes E. Effect of
long-term and short-term progestagen treatment on follicular
development and pregnancy rate in cyclic ewes. Theriogenology
2001; 55: 993-1004.
- 25. Scaramuzzi RJ, Radford HM. Factors regulating ovulation rate
in the ewe. J Reprod Fertil 1984; 69: 353–367
- 26. Peters AR, Drew SB, Mann GE, Lamming GE, Beck NF.
Experimental and practical approaches to the establishment
and maintenance of pregnancy. J Physiol Pharm Suppl 1992;
43: 143-152.
- 27. Schmitt EJP, Barros CM, Fields PA, Fields MJ, Diaz T, Kluge
JM, Thatcher WW. 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 1996; 74: 1915-1929.
- 28. Cavalcanti A, Brandão FZ, Nogueira LAG, Fonseca JFD.
Effects of GnRH administration on ovulation and fertility in
ewes subjected to estrous synchronization. R Bras Zootec 2012;
41: 1412-1418.