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The objectives of the present study were to determine values for semen quality variables in the Eurasian perch (i.e., osmolality of seminal plasma as well as sperm motility characteristics analyzed with CASA system) in response to (1) the method of milt collection (stripping or catheterization) and (2) experimental contamination of catheterized semen with urine (0%, 5%, 10%, 20%, 30% and 50% of contamination). Additionally, the effect of short-term chilled storage of experimentally contaminated semen (during the 24 h post semen collection period) on motility characteristics was investigated. Use of a typical stripping procedure resulted in about 5%-10% contamination of semen with urine, what is much less compared with other species. Markedly lesser values of straight line velocity (VSL) and consequently less linearity of spermatozoa movement (LIN) in perch semen, however, occurred as a result of stripping (46 ± 4 μm/s and 38 ± 4% for VSL and LIN, respectively), when compared to sperm collected by catheterization (87 ± 5 μm/s and 77 ± 2% for VSL and LIN, respectively), indicate that even a 10% contamination of semen with urine may have negative effects on quality. Exposure of semen to urine resulted in a significant dose-dependent decrease in the percentage of motile spermatozoa (MOT) and both velocity variables (VSL and VCL). Amount of urine contamination also affected MOT, VCL, VSL and LIN value during short-term storage. In conclusion, it is important to avoid semen contamination by urine when using the stripping procedure in the Eurasian perch, either for controlled reproduction or sperm preservation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This study investigated how the inhibition of certain enzymes present in ide sperm influences sperm motility and the percentage of fertilised eggs. The enzymes studied were acid phosphatase (AcP), β-N-acetylglucosaminidase (β-NAGase) and lactate dehydrogenase (LDH). None of the inhibitors affected ide sperm motility parameters. The addition of gossypol (a LDH inhibitor) caused a considerable increase in the percentage of fertilised eggs (92-95% compared to 63% in the control). The inhibition of AcP caused a considerable decrease in fertility rate - at the highest inhibitor dose, the percentage of fertilised eggs decreased to 26%. A similar effect was seen after the addition of acetamide (a β-NAGase inhibitor), but in this case the highest dose caused complete inhibition of fertilisation. The results presented here indicate the importance of AcP and β-NAGase in the process of ide fertilisation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The effect of carp pituitary homogenate (CPH, n = 7) at a dose of 2.0 mg kg -1 and (D-Arg 6 , Pro 9 NET)-sGnRH + domperidone (Ovaprim, n = 7) at a dose of 0.5 ml kg -1 in northern pike (Esox lucius) sperm maturation under controlled conditions was examined. On the control group, 0.9% NaCl at a dose of 1.0 ml kg -1 (n = 7) was used. Sperm was collected 48 h following injection. Sperm quantity (total sperm volume, total sperm production and sperm concentration), sperm motility using the Computer-assisted sperm analysis (CASA) system and sperm and seminal plasma quality (sperm pH, seminal plasma osmotic pressure and seminal plasma pH) were determined for each male separately in each group. The results of the present study demonstrate that hormonal treatment had a positive effect on sperm maturation in northern pike, regardless of the hormonal preparation used. However, even though no differences were found in total sperm volume and total sperm production between fish injected with either CPH or Ovaprim, it should be highlighted that the highest progressive motile sperm (PRG), straight-linear velocity (VSL) and movement linearity (LIN) was noted in fish treated with Ovaprim. It was also found that it is possible to collect sperm from non-hormonally manipulated fish. However, in such a case, only a small sperm volume (around 0.1 ml) characterised by lowered PRG (below 40%) was noted. Considering the fact that only after Ovaprim application sperm motility with progressive movement of sperm above 50% was observed, the hatchery practice of collection of sperm 48 h after its application (at a dose of 0.5 ml kg -1 ) may be recommended., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The applicability of a programmable freezer for the increased-scale cryopreservation of common carp sperm was investigated. The effect of different equilibration times, cryopreservation methods, extenders, dilution ratios, activating solutions on the post-thaw motility of common carp sperm was investigated. The suitable post-thaw storage time-interval as well as fertilizing capacity of cryopreserved sperm was also examined. The motility, curvilinear velocity (VCL) and straightness (STR) values did not decrease significantly during 60min of equilibration neither in equilibrated nor thawed groups. Motility parameters of thawed sperm were similar using a conventional cryopreservation technique using a polystyrene box [motility (33%), VCL (47μm/s) and STR (88%)] and a programmable freezer: [motility (32%), VCL (54μm/s) and STR (89%)]. The highest motility and VCL was measured with a sugar based extender (grayling extender) at a ratio 1:9 (motility: 52%, VCL: 76μm/s) and 1:20 (motility: 49%, VCL: 76μm/s). The activating solution for cyprinids (ASC) could prolong sperm movement up for 2min. A storage time of six hours following thawing did not have a significant effect on the motility parameters of thawed carp sperm. Agglutination was observed during cryopreservation of an elevated volume of sperm whereas motility 47%, VCL 62μm/s and STR 91% were measured after thawing. Fertilization rate with thawed sperm (32%) was significantly lower compared to the control group (73%). According to our results, the developed method using a programmable freezer is suitable for the cryopreservation of elevated number of straws. However, carp sperm agglutination during freezing may have a negative effect on the fertilizing capacity., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The quality and fertilizing capacity of perch (Perca fluviatilis) sperm collected outside of the spawning season (off-season) and cryopreserved at a commercial scale, were tested. Basic parameters (equilibration time, dilution ratio, sperm concentration, post-thaw motility duration) which can have a significant effect on cryopreservation success were systematically investigated for effects on sperm quality using computer assisted sperm analysis (CASA). No significant decrease in progressive motility (pMOT) and straightness (STR) of fresh-diluted sperm was recorded among groups equilibrated for 0, 30 or 60min in an extender with cryoprotectants. Curvilinear velocity (VCL) was reduced significantly after 30min (30min: 146±15μm/s, 60min: 124±18μm/s) of equilibration compared to the control (174±9μm/s). After thawing, no decrease in pMOT or VCL was observed at different equilibration times in any of the analyzed groups. No correlation was observed among progressive motility, dilution ratios (p=0.7) and cell concentrations (p=0.1). The use of different activating solutions resulted in similar pMOT and VCL in the first 120s post-thaw. Nevertheless, post-thaw sperm motility was reduced after 30s using all activators. Motility parameters with low variation were recorded after thawing of 57 straws (pMOT: 37±7%, VCL: 92±10μm/s, STR: 89±3%). Ten randomly selected straws from commercial-scale cryopreservation resulted in a high fertilization rate (cryopreserved sperm: 72±14%, fresh control: 94±2%). An optimized commercial-scale cryopreservation protocol was successfully developed for Eurasian perch. The applicability of the off-season collected perch sperm for cryopreservation and fertilization was demonstrated., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Two different cryopreservation methods were compared and an optimal dilution ratio for the use of controlled-rate freezer (CRF) was established for Eurasian perch (Perca fluviatilis) sperm. Progressive motility (72 ± 15%) and curvilinear velocity (VCL, 146 ± 11 μm/s) of sperm cryopreserved with CRF did not reduce significantly compared to fresh sperm [progressive motility (90 ± 4%), VCL (173 ± 24 μm/s)]. On the other hand, progressive motility (62 ± 15%) and VCL (120 ± 21 μm/s) of sperm cryopreserved with the conventional floating frame technique were significantly lower when compared to the fresh control. Sperm in both cryopreserved groups showed significantly higher straightness [STR, CRF (84 ± 4%), frame (84 ± 2%)] than in the fresh control group (68 ± 4%). Perch sperm cryopreserved with CRF at a dilution ratio of 1:20 showed significantly higher progressive motility (49 ± 6%) than at a ratio of 1:5 (39 ± 6%) and showed significantly higher VCL (129 ± 11 μm/s) than at dilution ratios of 1:10 (112 ± 17 μm/s) and 1:5 (115 ± 9 μm/s)., (Copyright © 2014 Elsevier Inc. All rights reserved.)