Interrelation of Kinetic Parameters of Sperm of Servicing Bulls of the Holstein Breed with Its Fertilising Ability

Abstract

Sperm motility is an essential indicator that characterises the viability and structural integrity of sperm. This parameter is closely related to the fertilisation capacity of male germ cells, so its assessment is an integral part of sperm analysis. The purpose of this study is to investigate the possibility of predicting the fertilisation capacity of sperm of servicing bulls based on kinetic indicators. The study involved laboratory, zootechnical, and statistical methods. A significant variability in the kinetic parameters of sperm of servicing bulls was revealed – from 6.2 to 16.1%. The variation in the percentage of motile sperm in the ejaculate was 78.9-89.8; the percentage of progressive sperm – 50.0-74.5; velocity average path of sperm (VAP) – 132.6-163.7 µm/s; velocity straight line (VSL) – 99.2-138.2 µm/s; curvilinear velocity (VCL) – 223.7-272.3 µm/s; straightness of sperm (STR) – 73.9-85.0%, linearity (LIN) – 45.1-56.1%, wobble (WOB) – 57.2-63.8%. The difference between the minimum and maximum values for all the parameters under study is highly likely (P<0.001). A correlation between various kinetic parameters of sperm is established. Sperm movement rates and their relative values are largely conditioned upon the percentage of progressive sperm in the ejaculate (r=+0.231-0.761). VAP, VSL, and VCL indicators are interrelated (r=+0.550-0.887). The study investigated the average fertilising ability of the sperm of servicing bulls based on the results of insemination of 8,594 cows and 992 heifers in four farms of Zhytomyr and Kyiv oblasts, the variation was within 40.7-61.4%. It was proved that bulls with higher and average fertilising capacity are described by a higher percentage of progressive sperm in ejaculates, and VAP, VSL, and VCL indicators of sperm movement compared to bulls with low fertilising capacity. This pattern is confirmed by correlation analysis (r=+0.538-0.675). Kinetic parameters identified using the CASA system allow predicting the fertilising capacity of sperm and identify servicing bulls with reduced reproductive function