Yeah, I have also head about zinc supplements. He should atleast take a multivitamin every day. Also, I see there is fertilaid for men. I don't know how good that can be, but might be worth it to do some research on it.
MrsM - morphology has been quite subjective in the fertility world. A few years ago, they used to look for 30%!! Then they figured they can't find men who had such high numbers and they lowered it to 5%. My husband's came out to be 2.5%, but when I looked up online, they say average is between 2-5%. I wouldn't worry too much about it. I know another lady whose DH also had similar numbers, but she got preggo fine.