The researchers studied how different types of syringes affect horse sperm. They used rubber and plastic plungers in the syringes to see if it made a difference. They found that using rubber plungers decreased the movement of the sperm compared to using plastic plungers. However, the number of live sperm was not affected by the type of syringe used. When fresh extender was added after 45 minutes, the movement of the sperm increased.