Health checks , complete screenings, and a lot of prayer to find the right female and be a good breeder is more important.....why do you want to up the sperm ??? Proven old male ??
tehre is actually a perservative(I think anyway) that can go in with the sperm with artificial insemination. My friend did it with her english bulldogs and got like eight pups a litter vs four. her vet always uses it but I'm nto really sure what its called or know much elses about it.