Optimizing extenders for short-term storage of Sterlet (Acipenser ruthenus) sperm

Abstract

Considering endangered fish, storage of sterlet (Acipenser ruthenus) gamete is crucial, and investigating the most suitable extender for short-term storage of sperm is necessary. Therefore, the present study aimed to optimize suitable extenders for short-term storage of sterlet spermatozoa and determine the effects of storage periods and different extenders on spermatozoa motility parameters. The sperm of five mature males with good spermatozoa motility (∼80 %) were diluted with 20 different extenders having various Na+ and K+ concentrations and osmolality. Spermatozoa motility performances were assessed using a CASA system within 144 h storage at 0–2 °C. Undiluted sperm was used as a control. Seminal plasma Na+, K+, Ca2+ and Cl- concentrations were 17.56±10.12, 2.48±1.14, 0.11±0.06, and 6.20±3.42 mmol/L with osmolality of 35.60±20.70 mOsm/kg. A two-way ANOVA showed significant effects of storage time, extender, and their interaction on spermatozoa motility, curvilinear velocity (VCL), and straight-line velocity (VSL) (p3 mM resulted in lower spermatozoa motility performance. When the effects of storage time were studied, spermatozoa motility, VCL, and VSL in non-diluted sperm and those diluted with E18-E20 were decreased at 24–48 h and 72–96 h post-storage, respectively. This study shows that extenders with higher osmolality (39–62 mOsm/kg) and lower K+ (1 mmol/L) are the most suitable for storing sterlet sperm for a short period.

Keywords

• CASA
• Seminal plasma
• Spermatozoa motility
• Spermatozoa velocity
• Sturgeon