An investigation of equine sperm quality following cryopreservation at low sperm concentration and repeated freeze-thawing

Morse-Wolfe, B., Bleach, E.C.L. and Kershaw, C.M. (2022) An investigation of equine sperm quality following cryopreservation at low sperm concentration and repeated freeze-thawing. Journal of Equine Veterinary Science, 120. ISSN 07370806

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Abstract

Stallion spermatozoa are typically cryopreserved at 200 to 300 million sperm/ml; however recent advances such as intracytoplasmic sperm injection (ICSI) requires only one spermatozoon, wasting many, after thawing a whole straw. Cryopreserving at concentrations less than the current standard or refreezing thawed spermatozoa could maximize the use of genetically valuable animals and reduce waste. This investigation aimed to identify if lowering the sperm concentration for cryopreservation affected post-thaw quality after one and two freeze-thaw cycles. Nine ejaculates were collected from three fertile, “good freezer” stallions (post-thaw motility ≥35%) for experiment 1. Each ejaculate was split into eight treatments: five, 10, 20, 50, 100, 200, 300, 400 million sperm/ml and cryopreserved. Post-thaw: motility, viability, acrosome integrity and oxidative stress were assessed. Experiment 2, straws from experiment 1 (300 million sperm/ml) were thawed, diluted to 20 million sperm/ml or left undiluted (control) and refrozen. Post-thaw motility and viability were assessed. In experiment 1 sperm concentration did not affect post-thaw total motility (TM), progressive motility (PM) or viability at 50 to 400 million sperm/ml (P > .05). Whilst sperm concentrations of five to 20 million/ml did differ (post-thaw TM and PM). Both refreezing and reducing spermatozoa concentration, decreased TM, PM and viability (P < .05) after two freeze-thaw cycles. These results suggest cryopreserving at sperm concentrations as low as 50 million/ml maintains spermatozoa quality in good freezer stallions. Spermatozoa maintained some motility and viability when initially cryopreserved at 20 million sperm/ml and after two freeze-thaw cycles but research should investigate more optimal conditions.

Item Type: Article
Keywords: Stallion, Spermatozoa, Cryopreservation, Low concentration, Refreeze
Divisions: Animal Health, Behaviour and Welfare (from 1.09.21)
Depositing User: Mrs Rachael Giles
Date Deposited: 23 Feb 2023 14:06
Last Modified: 02 Dec 2023 04:30
URI: https://hau.repository.guildhe.ac.uk/id/eprint/17908

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