Effect of the addition of sulfated polysaccharides of animal and algal origin in the freezing medium of Colossoma macropomum (Characiformes: Serrasalmidae).

Abstract

The aim of this study was to evaluate the effects of supplementing the cryodiluent medium with sulfated polysaccharides (SP) extracted from marine algae (Ascophyllum nodosum or Solieria filiformis) and fish skin (Colossoma macropomum, Prochilodus brevis, or Oreochromis niloticus) on the cryopreservation of tambaqui semen. Twenty male tambaqui were used for semen collection and cryopreservation. For the fertilization assay, three males and five females were used. In Experiment 1, different concentrations of SP (0.0, 0.1, 0.25, 0.5, and 0.75 mg/mL) extracted from fish skin or marine algae were added to the freezing medium for C. macropomum semen. In Experiment 2, the results of sperm velocity analyses were used to select one concentration of each sulfated polysaccharide for use in fertilization trials. Among the treatments, A. nodosum at 0.75 mg/mL and C. macropomum at 0.50 mg/mL stood out, significantly improving sperm parameters such as motility, VCL, VSL, VAP, and LIN compared to the control group. S. filiformis, P. brevis, and O. niloticus also showed good results, with performance varying by concentration. Membrane integrity was higher in the algae-derived extract groups. Sperm morphology and DNA integrity did not differ significantly among groups. Fertilization rates remained high across all treatments (84.67% to 88.67%), with no statistically significant differences, indicating that the tested extracts did not compromise fertility. It was concluded that supplementation with SP from A. nodosum at 0.75 mg/mL and C. macropomum at 0.50 mg/mL, although all treatments showed similar fertility rates, is recommended as an additive to the semen dilution medium for tambaqui during freezing, as it improved important sperm parameters such as motility and VCL.