Hi,
How old is your cocker? Does he/she eat wet or dry food?
My boy is 4 and I feed him twice a day - breakfast and dinner.
He is not a great eater but he will not let himself starve. He eats dry food only with occasional treats. Most of the dog food packets will tell you how much to feed them and you can divide that into as many servings as you like.
I take it he's just a pet and doesn't 'work' on a farm or anything? Also, consider how often you're in to provide consistency with feeding times. But all in all, I'd say twice a day is fine but more if you wish or notice him hungry. Definitely no less than twice a day though!
