Hey icelicker,
I've tried several brands of whey protein powder, and I did not notice an increase in semen. Now, I looked over the ingredients and it is true what sethin says, there are things like L-arginine and Lysine and Leucine, etc. The amount per scoop, for On's 100% Whey Protein is around half a gram. Since I do take arginine and lysine supplements in addition to the protein powder, it turns out that half a gram is pretty little in comparison to the total amount that I consume daily. It is reasonable to say that these things might have some positive effects on semen amounts, but for me they have been fairly miniscule.
ManofPrinciples