Not entirely sure, but I have read that rats can't digest alfalfa hay, and that it's not good for them. I go on the idea, that pretty much everything you put in their cage, they may eat some of, even if by accident. I know they don't have a problem eating, and passing Timothy hay. Obviously, they don't need it in their diet, so I just give them a pinch of it to play in, and scatter in their cages. I know alfalfa has a different fatty content, and protein content. We used to feed it to our horses from time to time in the winter for extra calories, and stuff. And I know with rabbits, you usually only feed it to pregnant, sick, or very young rabbits. I'm just very cautious when it comes to that. But you may ask more experienced rat owners. I just keep Timothy hay for my rabbit, so I give a little to the rats from time to time. Not a lot. Also keep in mind that rats need lots of room in their cage too. If their cage is too small, with not enough places to hide and play, they may want out more than usual. Does your cage have levels, and plenty of houses and hammocks? You can also make levels with baskets from the dollar store and zip tie them to the sides. The more places to hide/sleep/play, the happier they will be when it's not out time.