How much testosterone is in sperm?

Semen (which is the fluid containing sperm) contains about 5 calories per ejaculation, total. Assuming that all of those 5 calories derive from protein, you'd be looking at 1.25g of protein, *max*. (there are 4 cals per 1 g protein). In reality, some of those calories are coming from enzymes, sugars, etc. So you'd probably be getting a bit less than 1 g of protein.