Boars were trained to mount a dummy for semen collection at 7 months age. After 4 weeks training period, semen was collected twice per week for 4 weeks using the gloved hand technique. The ejaculation duration and reaction time were recorded during each collection, and 4 layers of sterile gauze was used to filter the semen.
The gel-free volume of semen, sperm motility, pH and sperm viability were evaluated according to the methods of the world health organization (WHO) and those described by Kaeoket et al. [22, 23]. More than 200 spermatozoa and 3 fields under 10x microscope magnification (Olympus, Japan) were assessed for evaluation of sperm motility. Moreover, the sportive and linear motion sperm in each field were recorded using a counter. Sperm density,