Immediately after collection, semen was maintained in a water bath at 37 C, and the proportion of progressively motile sperm
(0–100%) was assessed. For this, a small drop of semen was placed on a pre warmed slide, covered with a cover slip, and
examined with a bright-field microscope (magnification 400; Olympus DX50, Olympus Corporation, Tokyo, Japan) with a heated stage.