Objectively Measured Sperm Motility and Sperm Head Morphometry in Boars (Sus scrofa): Relation to Fertility and Seminal Plasma Growth Factors

ABSTRACT: This study was conducted to investigate the relationships between results of computer‐assisted semen analysis (spermatozoal motility and sperm head morphometry) and fertility of boars. In addition, concentrations of insulin‐like growth factor (IGF)‐I and IGF‐II in seminal plasma were determined. The nonreturn rate (NRR) and the number of live‐born piglets were compatible with the requirements of artificial insemination for all boars included in this study. Semen samples of 12 boars (Pietrain; 3 ejaculates each) were evaluated for spermatozoal motility and sperm head dimensions using computer‐assisted methods. Native semen samples were centrifuged, and seminal plasma was frozen at −20°C until assayed for IGF‐I and IGF‐II by specific radioimmunoassays. Spermatozoa of boars with a higher NRR (>86%) had a significantly slower average velocity of motile spermatozoa when compared with that of boars with an NRR below 86%. High‐fertility boars (NRR > 86%) had significantly smaller sperm heads than did boars with an NRR below 86%, and their sperm heads were less elongated. Substantial concentrations of IGF‐I (8.4–22.2 ng/mL) and IGF‐II (12.1–19.8 ng/mL) could be measured in porcine seminal plasma; however, there was no correlation between IGF levels and semen parameters or individual fertility.