Hello, I've noticed over the past few months, since I switched to Oxbow, my rats have lost a tremendous amount of weight. They're way too skinny for my liking even with lab blocks mixed in, so I'm switching back to the lab block (Extrusion). They love the stuff and were a healthy size when on those. I told Mumsy that I'd like to order a bag of the Harland food but I was wondering, what exactly is it? A lab block? I'm worried about buying a 30 lb bag of food that my rats will refuse to the point of starving themselves again.