References

Amann RP, Pickett BW. Principles of cryopreservation and a review of cryopreservation of stallion spermatozoa. J Equine Vet Sci. 1987; 7:145-173 https://doi.org/10.1016/S0737-0806%2887%2980025-4

Barbacini S, Marchi V, Zavaglia G. Equine frozen semen: results obtained in Italy during the 1994–1997 period. Equine Vet Educ. 1999; 11:(2)109-112

Crowe CAM, Ravenhill RJ, Hepburn RJ, Shepherd CH. A retrospective study of artificial insemination of 251 mares using chilled and fixed time frozen-thawed semen. Equine Vet J. 2008; 40:572-576 https://doi.org/10.2746/042516408x281199

BEVA approved artificial insemination list. 2021. https://ebevahosting.org/wp-content/uploads/2021/11/A.I.-Letter-2021.pdf (Accessed 15 February 2022)

Ferrer MS, Lyle SK, Paccamonti DL, Eilts BE, Hosgood G, Godke RA. Persistent breeding-induced endometritis after hysteroscopic insemination in the mare. Reprod Dom Anim. 2012; 47:(5)732-739 https://doi.org/10.1111/j.14390531.2011.01951.x

Govaere JLJ, Hoogewijs MK, De Schauwer C, De Vliegher S, Van Soom A, Duchateau L, de Kruif A. Effect of artificial insemination protocol and dose of frozen/thawed stallion semen on pregnancy results in mares. Reprod Domest Anim. 2014; 49:(3)487-491 https://doi.org/10.1111/rda.12316

Horserace Betting Levy Board International Codes of Practice. Checklist for artificial insemination. 2022. https://codes.hblb.org.uk/index.php/page/158 (Accessed 15 February 2022)

Hollinshead FK, Hanlon DW. A single fixed-time insemination prior to ovulation results in higher pregnancy rates than post-ovulation insemination when using frozen-thawed semen. J Equine Vet Sci. 2018; 66:198-199 https://doi.org/10.1016/j.jevs.2018.05.088

Huber D, Amsler E, Vidondo B, Kaeser R, Wespi B, Sieme H, Burger D. Increase of pregnancy rate after multiple periovulatory inseminations in mares. Tierarztl Prax Ausg G Grosstiere Nutztiere. 2019; 47:18-24 https://doi.org/10.1055/a-0803-1211

Immonen I, Cuervo-Arango J. Effect of timing of postovulatory insemination relative to human chorionic gonadotropin/buserelin treatment with 1 straw of frozen-thawed semen on mare fertility. J Equine Vet Sci. 2020; 87:1-5 https://doi.org/10.1016/j.jevs.2019.102900

Köhne M, Mönnig F, Papin J, Schöniger S, Tönissen A, Rohn K, Martinsson G, Schoon HA, Sieme H. Effects of hysteroscopic and uterine body insemination on the presence of selected immune cells in the equine endometrium. J Equine Vet Sci. 2020; 90:1-7 https://doi.org/10.1016/j.jevs.2020.103023

Lewis N, Morganti M, Collingwood F, Grove-White DH, McGregor Argo C. Utilization of one-dose postovulation breeding with frozen-thawed semen at a commercial artificial insemination center: pregnancy rates and postbreeding uterine fluid accumulation in comparison to insemination with chilled or fresh semen. J Equine Vet Sci. 2015; 35:(11–12)882-887 https://doi.org/10.1016/j.jevs.2015.07.008

Loomis PR. The equine frozen semen industry. Anim Reprod Sci. 2001; 68:191-200 https://doi.org/10.1016/s0378-4320(01)00156-7

Loy RG. Characteristics of post partum reproduction in the mare. Vet Clin North Am Large Anim Pract. 1980; 2:345-359 https://doi.org/10.1016/s0196-9846(17)30167-2

Morris LHA, Tiplady C, Allen WR. Pregnancy rates in mares after a single fixed time hysteroscopic insemination of low numbers of frozen-thawed spermatozoa onto the uterotubal junction. Equine Vet J. 2003; 35:197-201 https://doi.org/10.2746/042516403776114162

NHS Fife. Procedure for the safe storage, use and transport of liquid nitrogen. 2019. https://www.nhsfife.org/about-us/policies-and-procedures/procedures/procedure-for-the-safe-storage-use-and-transport-of-liquid-nitrogen/ (Accessed 15 February 2022)

Newcombe JR, Paccamonti D, Cuervo-Arango J. Reducing the examination interval to detect ovulation below 12 hours does not improve pregnancy rates after postovulatory insemination with frozen/thawed semen in mares. Anim Reprod Sci. 2011; 123:(1–2)60-63 https://doi.org/10.1016/j.anireprosci.2010.11.004

Newcombe JR, Kelly GM. Influence of mare, stallion, dose and interval on post-insemination uterine neutrophil counts. Pferdeheilkunde. 2016; 32:(1)26-28 https://doi.org/10.21836/PEM20160104

Pycock JF, Newcombe JR. Assessment of the effect of three treatments to remove intrauterine fluid on pregnancy rates in the mare. Vet Rec. 1996; 138:320-323 https://doi.org/10.1136/vr.138.14.320

Reger HP, Bruemmer JE, Squires EL, Maclellan LJ, Barbacini S, Necchi D, Zavaglia G. Effects of timing and placement of cryopreserved semen on fertility of mares. Equine Vet Educ. 2003; 15:(2)101-106

Samper JC, Gomez I, Sanchez R. Rectally guided or hysteroscopic insemination is there a difference?. J Equine Vet Sci. 2008; 28:640-644

Sieme H, Schafer T, Stout TA, Klug E. Waberski D. The effects of different insemination regimens on fertility in mares. Theriogenol. 2003; 60:1153-1164

Sieme H, Bonk A, Hamann H, Klug E, Katila T. Effects of different artificial insemination techniques and sperm doses on fertility of normal mares and mares with abnormal reproductive history. Theriogenol. 2004; 62:915-928

Squires E, Barbacini S, Matthews P, Byers W, Schwenzer K, Steiner J, Loomis P. Retrospective study of factors affecting fertility of fresh, cooled and frozen semen. Equine Vet Educ. 2006; 18:(2)96-99

Watson ED, Barbacini S, Berrocal B, Sheerin O, Marchi V, Zavaglia G, Necchi D. Effect of insemination time of frozen semen on incidence of uterine fluid in mares. Theriogenol. 2001; 56:(1)123-131

Veterinary
Breeding

Breeding with frozen semen: what are the considerations?

02 March 2022
Clinical
7 mins read
02 March 2022
Volume 6 · Issue 2

Abstract

The use of frozen semen is sometimes the only available option for artificial insemination. Compared to fresh or chilled semen, the use of frozen semen has previously been reported to have lower pregnancy rates, and higher rates of post-breeding inflammation and uterine fluid accumulation. More recent studies have found that pregnancy rates are indeed lower than with fresh semen, but are comparable if not better than chilled semen, with little evidence of increased complications. Several factors can affect conception rates and the practicality of using frozen semen, and these limitations should be explained to the client in advance. This review covers essential requirements applicable to artificial insemination with frozen semen, as well as mare and stallion factors that contribute to the adaptation of appropriate insemination protocol.

Insemination with fresh semen has a per-cycle pregnancy rate of up to 76% (Jasko et al, 1992), and could therefore be regarded as the gold standard. However, vets are often faced with less-than-ideal conditions and chilled and frozen semen are often used instead.

The evidence on per-cycle pregnancy rates for chilled and frozen semen are conflicting (Table 1). Some studies have reported higher per-cycle pregnancy rates for chilled semen (Jasko et al, 1992; Loomis, 2001), while others reported higher pregnancy rates per-cycle, as well as higher seasonal pregnancy rate, in mares arti-ficially inseminated with frozen semen (82% frozen, 69.6% chilled, p=0.02; Crowe et al, 2008). Before considering the factors that may affect pregnancy rates, the following areas should be considered as these could potentially eliminate frozen semen as an option or have a large impact on the insemination protocol used.

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semen
breeding
artificial insemination
conception