High ambient temperature and humidity associated with early embryonic loss after embryo transfer in mares.
Abstract: Increased ambient temperatures has been identified to contribute to reproductive outcomes for several domesticated species, but its impact on equine reproduction has not been previously investigated. Therefore, this study aimed to examine the relationship between ambient climatic conditions, as measured by temperature-humidity index (THI) between day 7 and day 14 of gestation, and early embryonic loss (EEL) in recipient mares undergoing embryo transfer. The study examined records from 834 embryo transfers at an equine breeding facility in Victoria, Australia. Early embryonic loss was defined as a negative transrectal ultrasound on day 14 of gestation after an embryo was transferred on day 7. Both maximum THI on the day of transfer (day 7) and mean THI between day 7 and day 14 were investigated for association with the outcome of EEL using multivariable logistic regression, controlling for confounders including embryo age and quality, recipient mare quality and embryo transfer quality. EEL was observed in 21% of embryo transfers. A five-unit increase in maximum THI on the day of transfer was associated with an 18% increase in the odds of EEL (p = 0.01). Similarly, the odds of EEL increased by 25% for each five-unit increase in mean THI between day 7 and 14 (p = 0.003). As both single and cumulative episodes of high THI were associated with increased EEL in embryo transfer mares from this equine breeding facility, further studies are warranted to identify similar effects in a broader population, establish causality and evaluate possible mitigation strategies in anticipation of heat waves.
Copyright © 2022 Elsevier Inc. All rights reserved.
Publication Date: 2022-05-24 PubMed ID: 35661481DOI: 10.1016/j.theriogenology.2022.05.014Google Scholar: Lookup
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- Journal Article
Summary
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The research investigates the impact of increased ambient temperature and humidity on early embryonic loss (EEL) in mares after an embryo transfer. Higher temperature-humidity index (THI) between the 7th and 14th day of gestation was found to increase the odds of EEL.
Study Overview
- This study attempts to understand the influence of the climatic conditions on reproductive outcome, specifically on EEL in mares post embryo transfer, given the increasing rates of ambient temperatures. The focus is on two parameters – THI on the day of transfer (Day 7) and mean THI between Day 7 and Day 14.
- The subjects of the study were recipient mares at a breeding facility in Victoria, Australia. Records of 834 embryo transfers were reviewed for this research.
- The condition of EEL was identified as a negative ultrasound test on the 14th day post embryo transfer which occurred on the 7th day.
Method and Findings
- A multivariable logistic regression was used to analyze the association between THI and EEL. This approach helped control potential confounding factors such as embryo age and quality, mare quality and embryo transfer quality.
- The results showed that an increase in maximum THI on the day of transfer by five units resulted in an 18% increase in the chances of EEL. Also, a similar rise in mean THI between the 7th and 14th day increased EEL odds by 25%. Out of all the embryo transfers, 21% were observed to have EEL.
- Although the study was conducted on a concrete population (mares at a certain equine breeding facility), the researchers suggest that similar effects could be possible in a broader context. Hence, further study is needed to confirm this across a wider population and to identify any potential preventive measures that could be taken during heatwaves.
Significance of the Research
- The research holds importance because the impacts of rising ambient temperatures on reproductive health of domestic animals, and specifically mares in this case, can provide insights that may help minimize the risk of embryo loss during the critical gestation period.
- It also throws light on the need to prepare and plan for heatwaves and devise effective strategies to prevent or minimize such embryonic losses in mares.
Cite This Article
APA
Yu K, Pfeiffer C, Burden C, Krekeler N, Marth C.
(2022).
High ambient temperature and humidity associated with early embryonic loss after embryo transfer in mares.
Theriogenology, 188, 37-42.
https://doi.org/10.1016/j.theriogenology.2022.05.014 Publication
Researcher Affiliations
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia.
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia.
- Goulburn Valley Equine Hospital, Congupna, Victoria, Australia.
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia.
- Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia. Electronic address: christina.marth@unimelb.edu.au.
MeSH Terms
- Animals
- Embryo Transfer / veterinary
- Embryo, Mammalian
- Female
- Horses
- Hot Temperature
- Humidity
- Temperature
Conflict of Interest Statement
Declaration of competing interest To the best of their knowledge, the authors are not aware of any conflicts of interest associated with this work.
Citations
This article has been cited 4 times.- Lawson EF, Pickford R, Aitken RJ, Gibb Z, Grupen CG, Swegen A. Mapping the lipidomic secretome of the early equine embryo. Front Vet Sci 2024;11:1439550.
- Xie C, Huang C, Yan L, Yao R, Xiao J, Yang M, Chen H, Tang K, Zhou D, Lin P, Wang A, Jin Y. Recipients' and Environmental Factors Affecting the Pregnancy Rates of a Large, Fresh In Vitro Fertilization-Embryo Transfer Program for Dairy Cows in a Commercial Herd in China. Vet Sci 2024 Sep 5;11(9).
- Alkhadrawy JMH, Aboelmaaty AM, Abou-Ahmed MM, Ghallab AM. Effect of breeding season and age on follicular dynamics and hemodynamics in embryo donor mares subjected to luteolysis after embryo flushing. Open Vet J 2024 Mar;14(3):852-865.
- Kang H, Zsoldos RR, Sole-Guitart A, Narayan E, Cawdell-Smith AJ, Gaughan JB. Heat stress in horses: a literature review. Int J Biometeorol 2023 Jun;67(6):957-973.
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