With Bobby cocker, he couldn’t digest the ground bone , in the Durham food frozen packs, many varieties, which are actually visible sharp pieces. They came through whole. Some mixes include vegetables and ‘rusk’. I too , worried about the fat content. I tried mixing my own , following approved recipes,but got fed up. I only tried for a month.
I’m glad I didn’t stick at it, because I might have blamed myself for his later kidney condition.
You can use ground eggshell instead of bone, but I wasn’t happy about getting the correct ratios involved in calcium, phosphorus , potassium,salt etc.
One of my rescue terriers would only eat raw at first, but couldnt cope with bone either.