Years ago had a female Great Dane (Luca Bratzi), about 125-130 pounds, and fairly lean. Great dog, but ate regular old dog food. Been a while so I can't recall what.
More recently had a big mutt (possibly Saint Bernard/rotty/shepherd-ish) - he was a Humane Society rescue who turned out to be the best dude, all-time. Adopted him at 90 pounds at 1.5 years. Fluctuated between 100-110 as a grown fella. He developed seizures around age 4, then we switched to an all-natural diet (loved chicken, eggs, potatoes, carrots, that sorta thing). He lived to 10, and passed 2.5 years ago.
Ready to adopt again. Reaching out about a little fella who is a 2-year-old Spanish mastiff. They say he's 170 pounds - looks a little sedentary in pics - doesn't look active, even for the larger breed. Thinking 150-160 once he's up to speed, active, etc.
Anyhow, I'm starting to read about food options for the best health for guys like this, cost factors of all natural, etc. Not cheap, of course, Any hybrid diets. Wondering if any BBIers navigate this path with bigger pups who typically eat, eat, then eat some more.