Effect of Chilling Temperature on the Long-Term Survival of Rabbit Spermatozoa held Either in a Tris-Based or a Jellified Extender

Contents As the preservation of the fertilizing capacity of rabbit spermatozoa for several days after semen collection remains a major target for the artificial insemination programs of rabbit breeding, a study was conducted to compare the efficacy of 5 or 15 degrees C as holding temperature in lengthening the preservability of rabbit semen quality during 192 h of storage both in a solid (Cunigel) and a liquid (Tris-Citric acid-Glucose; TCG) extender. Six pooled semen samples (two ejaculates/male; two-three males/pool) were taken and made four aliquots: two aliquots were tenfold diluted with the TCG extender, whereas the other two were tenfold diluted with the Cunigel extender. One aliquot per diluent was stored at 5 degrees C and the second one at 15 degrees C. Sperm motility (light microscope), viability (SyBr-PI staining), plasma membrane functional integrity (Hypo-osmotic swelling test) and acrosome integrity (PSA-FITC staining) were recorded at 0, 48, 120 and 192 h of storage. In liquid-stored spermatozoa, mass motility and viability were significantly higher (p < 0.05) in samples stored at 5 degrees C than at 15 degrees C at all the storage times; at 5 degrees C resulted also higher (p < 0.05) the percentages of both forward motility at 48 h and sperm functional integrity at 120 and 192 h of storage, whereas chilling temperature did not affect acrosome integrity. With the Cunigel extender, all the semen qualitative parameters were significantly higher in sample stored at 5 than 15 degrees C over storage time (p < 0.05); only acrosome integrity at 192 h was not different according to the chilling temperatures. In conclusion, 5 degrees C were better than 15 degrees C for the long-term storage of rabbit semen both in the TCG and Cunigel extender.