Sperm count higher from ejaculations resulting from sexual intercourse than from masturbation. The less time a couple has spent together since their last intercourse, the higher the sperm count in the male"s ejaculation (sperm competition?) A males likelihood of fertilization success depends on the number of sperm he produces and inseminates. Last male sperm precedence - the last male to mate with a female is most likely to inseminate the female. First male sperm precedence - first male to mate with a female is most likely to inseminate the female. Found that earlier mating males had higher success (not necessarily the first mating male) Some researchers argue that sperm precedence doesn"t truly exist for any mammals. Say it"s by chance because there are a lot of things that go into insemination. When the female ovulates and when she mates in relation to this ovulation. Molecula r changes to sperm that allow it to fuse with the egg for fertilizati on.