I'm not really sure, but I suppose that could be a reason. I can't imagine they taste any different lol if it's possible for you I guess you'll just have to get white rats from now on! I get mine from a local reptile shop who breeds BPs and feeders so I call in advance and they freeze however many I want. They have so many different colored rats that I'm sure they'd pick out white ones if I needed them. Do you buy from a rat breeder or the pre-boxed ones from pet stores??