Reproduction in domestic animals = Zuchthygiene2026; 61 Suppl 3(Suppl 3); e70260; doi: 10.1111/rda.70260

Comparative Susceptibility of Donkey and Horse Sperm to Liquid-Storage Temperature.

Vallejo-Soto, P
·
González Ariza, A
·
Vilela, BRN
·
Montero-Palma, C
·
Rodríguez González-Miranda, R
·
Pérez-Aguilera, V
·
Crespo-Castejón, F
·
Hidalgo, M
·
Dorado, J
·
Ortiz, I

Abstract: Preservation protocols for donkey sperm are based on those developed for horses, despite potential interspecific differences in cooling tolerance. This study compared horse and donkey sperm during long-term storage at 5°C and 17°C. Ejaculates from four stallions and four jacks (n = 16) were centrifuged, resuspended in skimmed milk-based extender, and stored at both temperatures. Sperm motility, plasma and acrosome membrane integrity, and morphology were evaluated after 1, 2 and 7 days. Fresh semen parameters showed no interspecific differences (p > 0.05). At 5°C, donkey sperm showed reduced motility and membrane integrity from Day 1, whereas horse sperm parameters remained stable at both temperatures up to Day 2. After 7 days, horse doses stored at 5°C maintained significantly higher quality. In conclusion, donkey sperm was more sensitive to storage at 5°C than horse sperm, highlighting the need for species-specific preservation strategies.

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Publication Date: 2026-10-01 PubMed ID: 42816916PubMed Central: PMC13627757DOI: 10.1111/rda.70260Google Scholar: Lookup

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Summary
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Journal Article
Comparative Study

Summary

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Overview

This study investigates how donkey and horse sperm differ in their tolerance to liquid-storage temperatures commonly used for preservation.
It finds that donkey sperm is more sensitive to cold storage at 5°C compared to horse sperm, indicating that preservation protocols for donkeys should be tailored specifically rather than borrowed from horses.

Background and Purpose

Preservation of sperm is crucial for assisted reproduction and breeding programs in equine species.
Currently, donkey sperm storage methods are based on protocols originally developed for horses, assuming similar responses to cooling.
However, physiological differences between species might affect sperm viability during storage at low temperatures.
The study aimed to directly compare how donkey and horse sperm respond to storage at two temperatures common for liquid storage: 5°C (cold storage) and 17°C (mild cooling).

Experimental Design

Semen samples were collected from four stallions (horses) and four jacks (male donkeys), making a total of 16 ejaculates.
Samples were centrifuged and resuspended in a skimmed milk-based extender, a medium supporting sperm preservation.
Aliquots of the extended semen were stored at two different temperatures: 5°C and 17°C.
Sperm quality parameters were assessed on days 1, 2, and 7 after storage.
Parameters measured included:
- Sperm motility—ability of sperm to move properly, crucial for fertilization.
- Plasma membrane integrity—indicating sperm cell viability and functionality.
- Acrosome membrane integrity—a key factor for sperm to penetrate the egg.
- Sperm morphology—shape and structural normality of sperm cells.
Initial (fresh) semen quality was also compared to ensure no baseline species differences.

Key Findings

Fresh semen from donkeys and horses showed no significant differences before storage, implying any changes were due to storage conditions.
At 5°C:
- Donkey sperm showed a rapid decline in motility and membrane integrity starting from the first day of storage.
- Horse sperm maintained stable motility and membrane integrity for at least two days.
- After 7 days, horse sperm stored at 5°C had significantly better quality compared to donkey sperm.
At 17°C:
- Horse sperm quality parameters remained stable up to day 2, similar to 5°C storage.
- The study does not highlight as much decline for donkey sperm at this temperature within the same timeframe.

Conclusions and Implications

Donkey sperm is more sensitive to cold storage at 5°C than horse sperm, indicating that equine species differ in their tolerance to preservation temperatures.
This difference suggests that equine reproductive technologies should develop species-specific preservation protocols rather than applying horse-based methods to donkeys.
Improving donkey sperm preservation could enhance breeding efficiency and genetic resource management for donkeys.
Future research could explore alternative extenders, additives, or storage temperatures tailored to donkey sperm physiology for enhanced preservation outcomes.

Cite This Article

APA

Vallejo-Soto P, González Ariza A, Vilela BRN, Montero-Palma C, Rodríguez González-Miranda R, Pérez-Aguilera V, Crespo-Castejón F, Hidalgo M, Dorado J, Ortiz I. (2026). Comparative Susceptibility of Donkey and Horse Sperm to Liquid-Storage Temperature. Reprod Domest Anim, 61 Suppl 3(Suppl 3), e70260. https://doi.org/10.1111/rda.70260

Publication

Reproduction in domestic animals = Zuchthygiene

ISSN: 1439-0531

NlmUniqueID: 9015668

Country: Germany

Language: English

Volume: 61 Suppl 3

Issue: Suppl 3

Pages: e70260

PII: e70260

Researcher Affiliations

Vallejo-Soto, Pilar

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

González Ariza, Antonio

Agropecuary Provincial Centre, Diputación Provincial de Córdoba, Córdoba, Spain.

Vilela, Blenda R N

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

Montero-Palma, Carlos

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

Rodríguez González-Miranda, Rocío

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

Pérez-Aguilera, Verónica

Centro Militar de Cría Caballar de Ávila, Cría Caballar de Las Fuerzas Armadas, Ávila, Spain.

Crespo-Castejón, Francisco

Centro Militar de Cría Caballar de Ávila, Cría Caballar de Las Fuerzas Armadas, Ávila, Spain.

Hidalgo, Manuel

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

Dorado, Jesús

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

Ortiz, Isabel

Veterinary Reproduction Group (AGR-275), Department of Animal Medicine and Surgery, Faculty of Veterinary Medicine, Universidad de Córdoba, Córdoba, Spain.

MeSH Terms

Animals
Male
Horses
Semen Preservation / veterinary
Semen Preservation / methods
Equidae
Spermatozoa / physiology
Sperm Motility
Temperature
Semen Analysis / veterinary
Acrosome
Species Specificity

Grant Funding

PID2020-116090RB-I00 / Ministerio de Ciencia e Innovación
FPU23/03472 / Ministerio de Universidades
FinanceCode001 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES)

Conflict of Interest Statement

The authors declare no conflicts of interest.

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