The effect of temperature on the motility and viability of sperm

In specimens of semen kept at 37 degrees C sperm lose their motility and viability. If kept at 4 degrees C they retain their viability but lose their motility from so-called thermal shock. The best temperature to keep semen in order to preserve sperm motility is 20 degrees C. Loss of motility at 37 degrees C is not entirely prevented by prevention of bacterial contamination with antibiotics.