The Effect of Apilarnil Administration on Spermiation and Semen Quality in Sterlet (Acipenser ruthenus)

The severe decrease in natural sturgeon stocks has led to intensified efforts toward the development of sturgeon aquaculture and the application of reproductive biotechnologies to ensure sustainable production. In cultured male Acipenser ruthenus (sterlet), spermiation must be hormonally induced to obtain high-quality semen; however, reducing hormonal dosages while maintaining or improving sperm quality remains a major challenge. In this study, we investigated the effects of reduced doses of carp pituitary extract (CPE) and luteinizing hormone-releasing hormone agonist (LH-RH) combined with Apilarnil supplementation on spermiation and semen quality in A. ruthenus. Semen volume, pH, sperm concentration, total sperm output, total motility, and spermatozoa velocity were evaluated. Administering a reduced CPE dose (1.1 mg·kg−1) combined with 1 g of Apilarnil significantly increased semen volume, sperm concentration, and total sperm output, as well as improved sperm kinematic parameters (total motility and velocity) compared with the conventional hormonal protocol. Furthermore, treatments using 50% of the standard LH-RH dose supplemented with 1 g or 2 g of Apilarnil resulted in significantly higher sperm motility and velocity than observed in the control group. These results demonstrate that Apilarnil supplementation allows for a substantial reduction in exogenous hormonal doses while enhancing spermiation efficiency and semen quality in sterlet, supporting the spermiation-induction protocol for sturgeon aquaculture.