Wow. For a moment there I wasn't sure if you meant fancy rats or rats like rat terriers =D I had pet rats most of high school and then all of college and will always have a soft spot for the little critters -they are great pets, especially if for some reason you can't have dogs! But it can get a little tiresome having to explain to practically everyone that these are rattus norvegicus and not rattus rattus
Anyways, from what I've read, active dogs require a high protein diet to keep up -not that I would know from experience as both my dogs are pretty sedentary
but I do know that too much protein is a big no-no for rats and can cause a whole lot of problems... Which is why dog food is usually not recomended. I'd say spend the extra $10 a month and get them a good rat feed at a petstore and supplement with fresh veggies and fruit and grains -not too much nuts (protein,again) and a little chocolate does wonders for their colds!
I hope this helps...? All I can say is that most of my rate came from petstores and they still lived over 2 years (more like 3-4 years), which is pretty impressive for rats, so I like to think it was thanks to excersice and diet
So, are we actually talking fancy rats? Because if not, I just struggled with my phone's touchscreen to spew useless knowledge...
Anyway, good luck with your crew!