The semen cryobank realised within the LIFE Nat.Sal.Mo. project is an important tool to safeguard the genetic integrity of Mediterranean trout (S cettii) at risk of extinction, thanks to its practical use in the supportive breeding. This practice consists in the use of artificial reproduction (AR) to support the natural one. In particular, frozen semen doses in combination with cross-fertilization schemes are used in AR to maximize the genetic variability of offspring to be used in restocking activities. Generally, in AR practices the use of a basic saline solution (D532) is recommended as artificial fertilization medium (AFM) to boost sperm motility. However, in order to maintain a repro-ductive microenvironment (RM) as similar as possible to the natural one we focused on the use of ovarian fluid (OF) alone as activation medium to sperm motility. Therefore, the aim of the present study was to evaluate the effects of only OF on the post-thaw sperm motility of S. cettii compared to D532 and a combi-nation of them at 50% (OF50%).Sperm samples from 5 males were frozen using a freezing pro-tocol optimised in our laboratory. Each sperm sample was thawed at 40 °C for 5 s and the motility was activated with OF100% and OF 50% of each female (N = 5) or D532, then analysed by CASA system. Within each treatment, the data obtained was compared with ONE-WAY-ANOVA, followed by Duncan’s test. To assess the fixed effects of male and female ID and their interaction, we used the GLM procedure. OF100% and OF50% enhanced (p < 0.05) respectively the total motility (50.4 ± 2%; 51.8 ± 1.9%) and dura-tion of movement (46.1 ± 1.5s; 46.1 ± 1.5s) than D532 (38.5 ± 3.2%; 31.2 ± 1.8 s); higher values (p < 0.05) of velocity parameters (VSL, VCL, VAP) were obtained with D532 than other treatments. Sperm traits varied depending on parental ID and interplay between male × female (p < 0.05).Although D532 boosted kinetic parameters more than OF, the authors retain that the sperm velocity could not be a key param-eter for a successful fertilization in our cross-fertilization system. In fact, in a controlled RM that already favours the gametes encounter, obtaining a greater number of post-thaw motile sperm/egg that move for a longer time could potentially increase the reproductive efficiency of S cettii. Thus, the use of OF alone in the AR could be a simple and effective activation/fertilization media to facilitate the management of riverbank operations, avoiding preparation, transport and use of AFM.
The supportive breeding of native Mediterranean brown trout (LIFE Nat.Sal.Mo project, Molise region): the effect of ovarian fluid on frozen sperm motility parameters during artificial fertilization
Giusy Rusco;Michele Di Iorio;Emanuele Antenucci;Letizia Lerza;Nicolaia Iaffaldano.
2023-01-01
Abstract
The semen cryobank realised within the LIFE Nat.Sal.Mo. project is an important tool to safeguard the genetic integrity of Mediterranean trout (S cettii) at risk of extinction, thanks to its practical use in the supportive breeding. This practice consists in the use of artificial reproduction (AR) to support the natural one. In particular, frozen semen doses in combination with cross-fertilization schemes are used in AR to maximize the genetic variability of offspring to be used in restocking activities. Generally, in AR practices the use of a basic saline solution (D532) is recommended as artificial fertilization medium (AFM) to boost sperm motility. However, in order to maintain a repro-ductive microenvironment (RM) as similar as possible to the natural one we focused on the use of ovarian fluid (OF) alone as activation medium to sperm motility. Therefore, the aim of the present study was to evaluate the effects of only OF on the post-thaw sperm motility of S. cettii compared to D532 and a combi-nation of them at 50% (OF50%).Sperm samples from 5 males were frozen using a freezing pro-tocol optimised in our laboratory. Each sperm sample was thawed at 40 °C for 5 s and the motility was activated with OF100% and OF 50% of each female (N = 5) or D532, then analysed by CASA system. Within each treatment, the data obtained was compared with ONE-WAY-ANOVA, followed by Duncan’s test. To assess the fixed effects of male and female ID and their interaction, we used the GLM procedure. OF100% and OF50% enhanced (p < 0.05) respectively the total motility (50.4 ± 2%; 51.8 ± 1.9%) and dura-tion of movement (46.1 ± 1.5s; 46.1 ± 1.5s) than D532 (38.5 ± 3.2%; 31.2 ± 1.8 s); higher values (p < 0.05) of velocity parameters (VSL, VCL, VAP) were obtained with D532 than other treatments. Sperm traits varied depending on parental ID and interplay between male × female (p < 0.05).Although D532 boosted kinetic parameters more than OF, the authors retain that the sperm velocity could not be a key param-eter for a successful fertilization in our cross-fertilization system. In fact, in a controlled RM that already favours the gametes encounter, obtaining a greater number of post-thaw motile sperm/egg that move for a longer time could potentially increase the reproductive efficiency of S cettii. Thus, the use of OF alone in the AR could be a simple and effective activation/fertilization media to facilitate the management of riverbank operations, avoiding preparation, transport and use of AFM.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
