A fructose-based extender protects Colossoma macropomum spermatozoa against chilling injuries

Our study assessed the efficiency of a formulated new extender in maintaining viability and morphological integrity of Colossoma macropomum spermatozoa under chilling storage. Semen was diluted in the test extender and BTS (TM) (Beltsville Thawing Solution) and exposed to a short-term storage at 4.6 +/- 0.6 degrees C for 96 hr. Both extenders were able to maintain 17% +/- 8% motile spermatozoa by the end of experiment. Sperm dilution in test extender did not affect the morphologically normal cells (61% +/- 6%) up to 48 hr of chilling, being higher than in BTS (TM) (50% +/- 6%) (p < 0.05). After 96 hr, samples kept in the test extender had 50% of normal spermatozoa, whereas those kept in BTS (TM) presented only 38% of normal cells. Chilling storage increased the incidence of cells with strongly coiled flagella in BTS (TM). Our study is the first to evaluate in detail the spermatozoa morphology as indicative of C. macropomum semen viability. The new extender was able to protect the spermatozoa against increase in coiled flagellum injuries.