The combination of CASA kinetic parameters and fluorescein staining as a fertility tool in cryopreserved bull semen

Abstract

Prediction of male fertility with in vitro semen quality parameters remains a challenge for the bull industry. Fluorescein staining and computer-assisted semen analysis (CASA) ensure kinetically proper and functionally objective results to improve spermatological parameter control. Therefore, we aimed to examine the CASA kinetic parameters and fluorescein staining of cryopreserved bull semen and its relationship with fertility. A total of 90 frozen straws from 5 Simmental bulls were evaluated. After semen was thawed, the motility, kinetic parameters, and insemination doses were evaluated by CASA; fluorescein stainings were evaluated using a fluorescein microscope. The 60th-day nonreturn rates (NRRs) were recorded for determination of pregnancy rates. There were significant differences in motility and kinetic parameters among bulls. Bull 3 had the lowest percentage of NRR and curvilinear velocity, straight line velocity, beat-cross frequency, and lateral head displacement parameters (P < 0.05). A positive correlation was detected between the pregnancy rate and some kinetic parameters. The correlation between the CASA parameters was determined as well. We concluded that various kinetic parameters obtained with CASA software system algorithms and fluorescein stainings can be linked to fertility. However, further research is needed to acquire a more precise link with fertility.