TY - JOUR
T1 - Optimal sperm–egg ratios for successful fertilization using fresh and cryopreserved sperm in wild anadromous Atlantic salmon (Salmo salar L. 1758)
AU - Erraud, Alexandre
AU - Cornet, Valérie
AU - Baekelandt, Sébastien
AU - Neus, Yvan
AU - Antipine, Sascha
AU - Lambert, Jérôme
AU - Mandiki, Syaghalirwa N.M.
AU - Kestemont, Patrick
N1 - Funding Information:
This study was supported by the project Meuse Salmon funded and provided by the Public Service of Wallonia , General Operational Direction of Agriculture, Natural Resources and Environment Nature and Forest Department . The authors also thank Mrs. C. Mayer for proof-reading the English.
Publisher Copyright:
© 2021
PY - 2022/2/25
Y1 - 2022/2/25
N2 - In the context of production of organisms for restocking purposes, it is essential to maximise the use of male semen while maintaining a high level of genetic diversity. Good management of the sperm/egg ratio seems therefore crucial, both for fresh and cryopreserved sperm. Recent studies in salmonid species have shown the potential for assisted reproduction with low or very low sperm to egg ratios, but an optimal sperm to egg ratio for a good reproductive efficiency remains to be established for many fish species. Here, the reproductive success of Atlantic salmon was assessed after fertilization with five low sperm/egg ratios ranging from 5 × 103 to 5 × 105 and one control ratio at 106. With fresh sperm, good eyed stage and hatching rates were obtained with a low ratio of about 5 × 104 sperm per egg. Nevertheless, a high inter-individual variability was observed up to a ratio of 105, underlining once more the importance to select males according to their sperm quality. According to the results obtained, it seems wise to use a sperm to egg ratio of around 5 × 105, i.e. only half the concentration that is recommended for assisted reproduction of the tested species. Cryopreservation undoubtedly has a negative effect on reproductive success as shown by reduced sperm quality of cryopreserved semen. The reproductive success follows a linear regression that is highly correlated to the sperm/egg ratio clearly indicating that it is not feasible in this species to use low sperm/egg ratios with cryopreserved semen. According to the equation defined by the linear regression, it would be necessary to use a sperm/egg ratio of the order of 2.36.106, i.e. 5 times more concentrated than fresh sperm, in order to reach an equivalent reproductive success of cryopreserved compared to fresh semen.
AB - In the context of production of organisms for restocking purposes, it is essential to maximise the use of male semen while maintaining a high level of genetic diversity. Good management of the sperm/egg ratio seems therefore crucial, both for fresh and cryopreserved sperm. Recent studies in salmonid species have shown the potential for assisted reproduction with low or very low sperm to egg ratios, but an optimal sperm to egg ratio for a good reproductive efficiency remains to be established for many fish species. Here, the reproductive success of Atlantic salmon was assessed after fertilization with five low sperm/egg ratios ranging from 5 × 103 to 5 × 105 and one control ratio at 106. With fresh sperm, good eyed stage and hatching rates were obtained with a low ratio of about 5 × 104 sperm per egg. Nevertheless, a high inter-individual variability was observed up to a ratio of 105, underlining once more the importance to select males according to their sperm quality. According to the results obtained, it seems wise to use a sperm to egg ratio of around 5 × 105, i.e. only half the concentration that is recommended for assisted reproduction of the tested species. Cryopreservation undoubtedly has a negative effect on reproductive success as shown by reduced sperm quality of cryopreserved semen. The reproductive success follows a linear regression that is highly correlated to the sperm/egg ratio clearly indicating that it is not feasible in this species to use low sperm/egg ratios with cryopreserved semen. According to the equation defined by the linear regression, it would be necessary to use a sperm/egg ratio of the order of 2.36.106, i.e. 5 times more concentrated than fresh sperm, in order to reach an equivalent reproductive success of cryopreserved compared to fresh semen.
KW - CASA motility
KW - Cryodamage
KW - Flow cytometry
KW - Salmo salar
KW - sperm–egg ratios
UR - http://www.scopus.com/inward/record.url?scp=85119960743&partnerID=8YFLogxK
U2 - 10.1016/j.aquaculture.2021.737758
DO - 10.1016/j.aquaculture.2021.737758
M3 - Article
AN - SCOPUS:85119960743
SN - 0044-8486
VL - 549
JO - Aquaculture
JF - Aquaculture
M1 - 737758
ER -