Stational variation on seminal characteristics in bagre rayado Pseudoplatystoma metaense (Telostei, pimelodidae)

Objective. To determine the quality variation, the ionic content and the osmolality in Pseudoplatystoma metaense seminal plasma during the reproductive period. Materials and methods. Sexually mature males were used during a reproductive season (march to august). The spermiation was induced with Carp Pituitary Extract (4 mg/kg). Volume (mL), masal motility (%), activation time (sc), spermatocrit (%), sperm concentration (106 sptz/?L) and viability (%) were evaluated. Also, motility (%) and individual speed through a Computer-Assisted Semen Analysis (CASA) were determined. The Osmolarity (mOsm/kg), the ions (Na+, Cl+, K+ and Mg2+) and the glucose concentration were determined in seminal plasma obtained by centrifugation at 14.000 g. The ions and glucose concentration were established through a reflectance system. Results. Sperm showed masal motility greater than 90%, with the lowest rapid linear progressive motility in the month of april (34.9±9.0%) and general levels of spermatozoa inmotile less than 10%. The seminal plasma showed an osmolarity of 259.3±3.5 mOsm/kg, with an average concentration of glucose and ions Na+, Cl+, K+ and Mg2+ of 142.7±2.8, 118±2.2, 4.8±0.4 and 0.33±0.0 mmol/L, respectively, during the reproductive season. Conclusions. The semen quality of bagre rayado presented no changes during the breeding season, and showed a high quality for the process of fertilization.