Cryobank of Mediterranean Brown Trout Semen: Evaluation of the Use of Frozen Semen up to Six Hours Post-Collection

Giusy Rusco,Roberta Iampietro,Nicolaia Iaffaldano,Alessandra Roncarati,Michele Di Iorio,Stefano Esposito

doi:10.3390/fishes6030026

Giusy Rusco, Roberta Iampietro + Show 4 more

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https://doi.org/10.3390/fishes6030026

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Journal: Fishes	Publication Date: Aug 2, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: University of Molise, Università di Camerino

Abstract

The aim of this study was to evaluate the effects of different cold-storage time intervals between collection and semen-freezing on both fresh and cryopreserved semen motility parameters and the post-thaw fertilizing ability of Mediterranean brown trout semen. The ejaculates were split into six aliquots and stored on ice from 1 to 6 h, until freezing. Fresh and post-thaw sperm motility was evaluated by a Computer-Assisted Sperm Analysis system, whilst the fertilizing ability was assessed by in vivo trials. In fresh semen, at 3 h of storage, a significant decrease of total motility, linear movement (STR, LIN) and beat cross frequency (BCF) was recorded, whilst the amplitude of lateral displacement of the spermatozoon head (ALH) underwent a significant increase. In frozen semen, no significant difference was observed for all the motility parameters evaluated, except for the total motility between 1 and 6 h of storage and the duration of sperm movement between 1 and 5 h. Cold-storage time did not significantly affect the percentage of live embryos following the use of frozen semen. In conclusion, our results showed that, if necessary, the Mediterranean brown trout semen can be frozen even until 6 h post-collection without losing its fertilizing ability.

Highlights

Over the last two decades, because of population reduction and extinction in many European countries, native salmonid species have been the focus of some important conservation projects [1,2,3,4,5]
The lowest percentage of ALH was registered at 2 h of storage, this resulted as significant in respect to the values recorded at 3, 4, 5 and 6 h (Figure 1G)
We evaluated the effect of different cold-storage time intervals that elapsed between collection and semen-freezing on both fresh and cryopreserved semen motility parameters and post-thaw fertilizing ability of Mediterranean brown trout semen

Summary

Introduction

Over the last two decades, because of population reduction and extinction in many European countries, native salmonid species have been the focus of some important conservation projects [1,2,3,4,5]. The introduction of alien invasive species, such as the Atlantic strain, and their interaction with the native fauna represents a major threat to the survival of this species, as the traits of their native gene pool are altered [7,8,9,10,11,12,13] In this context, the EU has recently funded the “LIFE” Nat.Sal.Mo project, which aims to ensure the recovery of native genetic variability and the conservation of the Mediterranean brown trout (S. macrostigma = S. cettii) inhabiting the Biferno and Volturno river basins (Molise region—Southern Italy). The restoration of the Mediterranean brown trout’s genetic integrity is among the main objectives of the project It is being realised through the use of artificial reproduction, using frozen semen from pure wild breeders in combination with appropriate fertilization schemes, as a strategy to maximize the genetic variability within the offspring and ensure the maintenance of the fitness within self-sustaining populations. In order to obtain an effective freezing protocol aimed at the implementation of the first European sperm cryobank for the native Mediterranean brown trout, a series of systematic studies were performed [14,15,16,17]

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