Hmmm... sperm production. Like most of our "self-experiments" we rely on hearsay, rumor and attempts to comprehend scientific studies. I imagine, that for a real test, you would have to increase, all by itself without altering any other diet matter, a certain food, herb, supplement, etc. and then ejaculate into a beaker for lab analysis and sperm count, maybe on a daily basis. Then change the supplement and repeat. Hard data is hard to come by (no puns intended, although after reading that sentence I had to chuckle just the slightest bit).
I once wrote on another forum about something that worked for me, I forget exactly what the subject was, and another poster, in a fit of ironic sarcasm wrote something like, "Right, so we rely on personal experience of others to guide us". Funny, my reaction was, that is one of the greatest godsends of the internet, listening to the personal experience of other real humans, instead of the reactions of lab rats in a laboratory setting.
Here's another thing I have found. It is so difficult , for me at least, to isolate one unique factor in my diet and lifestyle that has had a certain effect. Maybe its my own impatience and use of a shotgun technique.
That was my introduction. Now to the personal details. I take daily Ashwaganda. Rhodiola, Maca, Salvia, Silymarin and Gymnema Sylvestre along with Horny Goatweed (60% icariin). Now, I'm a type II diabetic whose sex life was in the toilet before going Paleo; at the moment I am able to have sex with orgasm daily, IF I want to... I don't do it, but it is now possible for me. This may not in any way equate to actual sperm count, but it may count for something.
Did I mention? I am 65 years old.