we have a highly active 4yr old border collie. She doesnt have a massive appetite.
She has 1/2 can of natures gift wet tin food and a bowl full of optimum dry food everynight. Occasionally i'll cook up some pasta or rice to add in. She doesnt eat evernight either. She eats when she wants. She's a healthy weight.
She gets meaty bones once a fortnight if i feel she hasnt eaten much.