"Two months of Baytril , tribulus 2 caps per day, flax seed w/lignans 1 tablespoon per day,both found at GNC store, Glycoflex the orignal formula. Then collect and see if he has improved , try this before you cut into him. This is all per my Repro Vet."
The above is from a 2010 posting, it's worth a try. There are several old threads on this. Search 'no sperm'. All the best!
Get a culture done asap and then go from there. Definitely would put him on a good fish oil, Vit E, Glyco Flex and IM A STUD supplement (Nature's Farmacy).