Done some quick research:
here :
Zinc is among the most important nutrient minerals in regards to male fertility. Zinc levels in the seminal plasma (the fluid in which the sperm exist) are directly related to sperm mobility,8 and dietary zinc restriction reduces both sperm count9 and seminal plasma volume.10 Moreover, infertile men with azoospermia (absence of living sperm),11 as well as those with oligospermia (low sperm count),12 may have decreased seminal zinc levels.
Several clinical trials have found zinc supplementation to be an effective fertility treatment. In one study, 14 infertile men with unexplained low sperm counts (below 40 million/mL) received 220 mg of zinc sulfate daily. After four months, there were significant improvements in sperm count and in the number of progressively motile and normal spermatozoa--and the wives of two men conceived.13
The results of other studies suggest treatment of a low initial plasma testosterone14 or surgical correction of a varicocele (abnormal dilation of spermatic cord veins) prior to zinc supplementation15 increase the chances of success. In this latter study, of the entire group of infertile men who received zinc, only those who had a varicocelectomy prior to starting zinc supplementation had significant improvements in sperm counts and mobility; in other words, sperm did not improve unless the men had both surgery and zinc supplementation.
And article here too on zinc for women ttc
And this site also gives suggestions on improving how to concieve naturally, including mention of zinc.
In fact there is quite a lot of stuff around. I just did a Google search for "zinc and conception" and it brought up loads.
HTH