So I think what I have been feeding them is Layer Crumbles with Scratch mixed in, and I was told recently to give them some cat food as well. Will the grower feed be called that or is there a special name I need to look for?
A couple of things. Each manufacturer has different names. Don't be too concerned about what a foodstuff is called but what the contained nutrients are. Guaranteed analysis is on the tag of every feed bag.
When your birds are actively laying, you're looking for a feed with about 16-17% protein and around 4% calcium. That describes most layer feeds. Feather fixer is slightly higher in protein and slightly lower in calcium (about 3%)
Any time they aren't actively building egg shells, they are fine on about
1% calcium. That's what is in every chicken feed except layer.
When molting, it helps to move up to about 18-20% protein. Feathers are about 93% protein.
If they aren't molting or building egg shells, 1% calcium and 15-18% protein is fine.
As far as the catfood goes, again, check the protein content. It can range from 15% to over 30%. If trying to boost protein, go for something in the 20s. Catfood contains nutrients for carnivorous felines, not omnivorous birds. Better would be a canned or fresh fish or any kind of meat, mealworms or crickets.