Any recommendations, what can be given to increase a males fertility?

Vitamin e and green lipped mussel apparently. Unsure on dosage but you can google it. Obviously it’s not ideal to breed from less fertile dogs if there’s no known environmental reason for it though.

Thanks. Already sired 3 litters. Will look up the mussel stuff.

Have you had a semen analysis done?

Once but not good. Will be doing again tho soon