Theriogenology2019; 127; 7-14; doi: 10.1016/j.theriogenology.2018.12.036

Analysis of factors affecting the pregnancy rate of mares after inseminations with cooled transported stallion semen.

Kareskoski, M
·
Venhoranta, H
·
Virtala, AM
·
Katila, T

Abstract: Artificial insemination (AI) with cooled stallion semen has increased markedly during the last decades in all countries, but fertility is often lower than when fresh semen or natural mating is used. The objective of this study was to examine field data (1634 ,cycles 523 Standardbred (SB) mares, 575 Finnhorse (FH) mares, and 90 stallions) using multivariable logistic regression for factors influencing the pregnancy rate (PR) after AI with cooled transported semen from SB and FH stallions. The PR per cycle for the material was 47%: Finnhorses 42% and Standardbreds 53%. When assessed with multivariable logistic regression analyses with a generalized linear mixed model, variables that affected the PR were breed, the number of inseminated estrus cycles, the percentage of progressively motile sperm (PMOT) in the ejaculate/AI dose at the time of shipment, and the number of progressively motile sperm in the AI dose at the time of insemination. In Standardbreds, variables that increased the per cycle PR were the number of AI per estrus cycle (multiple inseminations increasing the probability of pregnancy compared to only one insemination), the number of inseminated cycles, and PMOT in the AI dose at the time of insemination. In Finnhorses, the number of AI per estrus cycle (two and three inseminations increasing the probability of pregnancy compared to only one), the number of spermatozoa in the ejaculate and in the AI dose, and PMOT in the ejaculate/AI dose at the time of shipment increased the per cycle PR. Non-significant factors for the whole material included the type of artificial vagina (open-ended or closed), transport time, place of AI (stud farm or home stable), insemination done by veterinarian or technician, weekday, month, age of the mare (all age classes combined), age of the stallion, ejaculate parameters (sperm concentration, total number of sperm), and insemination dose parameters (volume proportion of seminal plasma, sperm concentration, PMOT, total number of sperm). In conclusion, breed, breeding opportunity in more than one cycle, more than one insemination/estrus, PMOT of the ejaculate/AI dose and the number of progressively motile sperm in the AI dose at the time of insemination are important for the outcome of inseminations with cooled semen.

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Publication Date: 2019-01-02 PubMed ID: 30611014DOI: 10.1016/j.theriogenology.2018.12.036Google Scholar: Lookup

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Journal Article

Summary

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This study evaluates multiple factors that could influence the success rate of artificial insemination (AI) in horses using cooled and transported semen from two different horse breeds. The research found that variables such as the breed, the number of insemination cycles, the quality of the sperm, and the frequency of insemination attempts can significantly influence the rate of successful pregnancies.

Background of the Study

The research was prompted by the rise in the use of Artificial Insemination (AI) with cooled stallion semen in recent years, despite the typically lower fertility rates compared to fresh semen use or natural mating.
The study collected and examined data from 523 Standardbred (SB) mares, 575 Finnhorse (FH) mares, and 90 stallions, totaling 1634 cycles.

Main Findings

The study found that both the breed of the horse and the number of inseminated estrus cycles could affect the pregnancy rate after AI using cooled semen. Specifically, Standardbred horses had a higher pregnancy rate per cycle (53%) compared to Finnhorses (42%).
Variables shown to increase the per-cycle pregnancy rate included the number of AIs per estrus cycle, the quantity of progressively motile sperm (PMOT) in the AI dose at the time of shipment, and the amount of PMOT in the AI dose at the time of insemination. Multiple inseminations per cycle improved the odds of achieving pregnancy.

Non-Significant Factors

The study also explored factors that did not significantly influence the pregnancy rate. These include the type of artificial vagina used for insemination, transport time for semen, place of AI, the professional performing the insemination, day of the week, month, age of the mare or stallion, and certain parameters of the ejaculate and insemination dose.

Conclusion

The paper concludes that breed, opportunity for multiple insemination cycles, more than one insemination per estrus, PMOT in the insemination dose, and the number of PMOT in the AI dose at the time of insemination were critical factors influencing successful inseminations with cooled semen.

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APA

Kareskoski M, Venhoranta H, Virtala AM, Katila T. (2019). Analysis of factors affecting the pregnancy rate of mares after inseminations with cooled transported stallion semen. Theriogenology, 127, 7-14. https://doi.org/10.1016/j.theriogenology.2018.12.036

Publication

Theriogenology

ISSN: 1879-3231

NlmUniqueID: 0421510

Country: United States

Language: English

Volume: 127

Pages: 7-14

Researcher Affiliations

Kareskoski, Maria

University of Helsinki, Faculty of Veterinary Medicine, Paroninkuja 20, 04920, Saarentaus, Finland.

Venhoranta, Heli

University of Helsinki, Faculty of Veterinary Medicine, Paroninkuja 20, 04920, Saarentaus, Finland.

Virtala, Anna-Maija

University of Helsinki, Faculty of Veterinary Medicine, PO Box 66, 00014, Helsinki, Finland. Electronic address: anna-maija.virtala@helsinki.fi.

Katila, Terttu

University of Helsinki, Faculty of Veterinary Medicine, Paroninkuja 20, 04920, Saarentaus, Finland. Electronic address: terttu.katila@helsinki.fi.

MeSH Terms

Animals
Female
Horses / physiology
Insemination, Artificial / veterinary
Logistic Models
Male
Multivariate Analysis
Pregnancy
Pregnancy Rate
Semen Analysis / veterinary
Semen Preservation / methods
Semen Preservation / veterinary

Citations

This article has been cited 5 times.

Brito LFC, Linardi RL, Rosales LAS, Balamurugan NS, Hernández-Avilés C, Ramírez-Agámez L. Evaluation of a Chemically Defined, Long-Term Extender for Liquid Storage of Stallion Semen. Reprod Domest Anim 2025 Sep;60(9):e70126.
doi: 10.1111/rda.70126pubmed: 41002042google scholar: lookup
Del Prete C, Attolini E, Merlo B, Iacono E, Nocera FP, De Martino L, Longobardi C, Damiano S, Longobardi V, Cocchia N, Pasolini MP. Post-Insemination Infusion of Wharton's Jelly Mesenchymal Stromal/Stem Cells-Derived Conditioned Medium: A Novel Approach for Improving Pregnancy Outcomes in Problem Mares. Vet Sci 2025 May 16;12(5).
doi: 10.3390/vetsci12050482pubmed: 40431575google scholar: lookup
Tukia E, Hallman I, Penttilä M, Hänninen S, Kareskoski M. RNA in situ hybridization of Escherichia coli in equine endometrial biopsies. Front Vet Sci 2023;10:1186051.
doi: 10.3389/fvets.2023.1186051pubmed: 37360403google scholar: lookup
Pemayun TGO, Mustofa I, Mahaputra L, Hermadi HA, Wijaya NMR, Mulyati S, Utama S, Restiadi TI, Rimayanti R. Fertility restoration of racing mare with persistent corpus luteum. Vet World 2021 Sep;14(9):2356-2361.
doi: 10.14202/vetworld.2021.2356-2361pubmed: 34840454google scholar: lookup
Weber KS, Wagener K, Blanco M, Bauersachs S, Bollwein H. A comparative analysis of the intrauterine transcriptome in fertile and subfertile mares using cytobrush sampling. BMC Genomics 2021 May 22;22(1):377.
doi: 10.1186/s12864-021-07701-3pubmed: 34022808google scholar: lookup