Efeitos da utilização da Arthrospira platensis no congelamento de sêmen de Piaractus mesopotamicus

Abstract

Piaractus mesopotamicus is a native fish with relevance in the Brazilian fish farming scenario and sperm cryopreservation can help the production chain by reducing gonadal asynchrony, optimizing inseminating doses, facilitating transport, among other advantages. As it is a technique that can cause damage to gamete structures through the generation of reactive oxygen species (ROS), cryoprotective solutions are used to reduce this damage, but supplementation with antioxidant substances is an alternative to improve the effectiveness of cryoprotective solutions. The aim of this study was to evaluate the supplementation of different concentrations of Arthrospira platensis in the sperm cryopreservation protocol of P. mesopotamicus fish. Six males (966.66g±179.50) from the Companhia Energética de Minas Gerais Fish Farm, located in the town of Itutinga-MG, were used. The semen was collected in January 2023 and then stored in a liquid nitrogen canister. In addition to the control group made up of a cryoprotective solution based on DMSO 5% and glucose 4%, 5 treatments were tested in which the control solution was supplemented with 2mg, 4mg, 6mg and 8mg of A. platensis. In addition to tests involving enzymatic activity, analyses were carried out on the sperm motility of fresh and post-thawed semen, membrane integrity, fertilization rate, larval development and the Tukey test at 5% significance. As far as the results are concerned, there was no statistical difference between subjective motility (100%) and motility duration (38-60s) between the sire samples. There was no statistical difference between the treatments and the control group in terms of general motility (34.3-50.80%); progressive motility (4.71-8.65%); VCL (57.66-66.13 μm/s); VSL (29.83-35.23 μm/s); VAP (44.63-49.29 μm/s); BCF (11.37-12.04 hz). There was no statistical difference in the enzymatic activities of SOD (61.01-109.58 U-SOD/mg) and GST (254.07- 383.41 U-GST/mg) in the different treatments. With regard to CAT, there was a difference between the group supplemented with 4mg (3.66 U-CAT/mg) and the groups supplemented with 2mg (7.48 U-CAT/mg) and 6mg (7.23 U-CAT/mg). However, there was no difference between the group supplemented with 8mg (5.42 U-CAT/mg) and the control group (5.48 U-CAT/mg). There was no statistical difference between the treatments and the control group for membrane integrity (49-63%). Regarding the fertilization rate, there was a statistical difference between the group supplemented with 8mg (70.33%) and the groups supplemented with 2mg (41.13%), 4mg (28.50%) and 6mg (36.50%), but there was no difference between the treatments and the control group (51.94%). There was no statistical difference between the treatments and the control group in terms of larval morphometry: total length (5.61-5.69mm); body height (0.88-0.95mm); anteroposterior diameter of the eye (0.37-0.39mm). Therefore, supplementation with A. platensis at the different concentrations tested in this study was not able to influence the parameters related to post-thaw sperm motility in P. mesopotamicus semen. Considering the results of the fertilization rate, more studies are needed on the use of A. platensis in the supplementation of cryoprotective solutions, as well as the need to apply other tests, such as oxidative stress markers and DNA integrity analyses.