Viability of rabbit spermatozoa stored in different extenders at 5⁰C or 15⁰C for up to 96 hours (#279)
The inability to preserve rabbit semen for more than 36 hours post-collection is a major limitation for artificial insemination programs in the rabbit meat industry. This study aimed to evaluate the effect of temperature and diluent on sperm motility and viability during liquid storage of rabbit semen over 96 hours. Semen was collected by artificial vagina from five rabbit bucks (three ejaculates/buck). Each ejaculate was initially evaluated for volume, a minimum sperm concentration of 300 x 106 spermatozoa/mL and at least 70% motile spermatozoa. Each of three equal aliquots was diluted 1:10 with a different extender: Extender A (313.79 mM TRIS, 103.07 mM citric acid.H20, 33.3 mM glucose and 80 mg/L kanamycin), Extender B (313.79 mM TRIS, 103.07 mM citric acid.H20, 33.3 mM glucose, 80 mg/L kanamycin and 14% gelatin) or Extender C (250.04 mM TRIS, 79.76 mM citric acid.H20, 69.38 mM glucose, 75.0 IU streptomycin and 166.2 IU G-Penicillin). The diluted semen was divided into two subsamples and stored at 5⁰C or 15⁰C. Sperm motility was evaluated by the CASA System (CASA: HTM IVOS v. 12) at 0, 24, 48, 72 and 96 hours of storage. The best two performing extenders were then assessed for viability using FITC-PNA/PI dual staining by the flow cytometer. Data were analyzed using a Linear Mixed Model (Genstat: VSN International.). After 96 hours, spermatozoa diluted in Extender C at 15⁰C displayed the highest percentage (±SEM) motility (62±1.3%, P<0.001). Extender B performed worst independent of storage temperature. There were no differences between the acrosome or membrane integrities for diluted semen regardless of extender or storage temperature. In conclusion, Extender C is the best diluent for the preservation of rabbit sperm motility when storing at 15⁰C for up to 96 hours. Further research will investigate the fecundity of the stored semen in rabbit artificial insemination programs.