Hay cubes do help wear down the teeth to an extent, but different varieties and textures of hay wear down different areas of the bite, so giving a different type of hay from time to time is best. As for the loss of interest in lava and loose hay, it's probably nothing to worry about as long as they're eating enough hay to keep digestion healthy, regardless of the type of hay. I think they are probably just excited to have something new and once the novelty of the cube form wears off, they'll be back to the other. My chin is really fair-weathered about all hay and chew toys and I found that rotating them keeps her interested. As soon as I think chin bagels are her favorite thing, she gets sick of them and becomes obsessed with palm shredders or pumice or willow! Same thing with hay, one minute she's all about Orchard grass, then she suddenly won't touch it and loves Timothy. Point is, just keep it interesting for them and they'll be fine. I forgot to mention, be careful not to feed them too much alfalfa, particularly if they are on an alfalfa-based pellet! A little bit is good for them, but it's much too high in protein to be a staple. Wow, sorry, I have a tendency to be long-winded, best of luck!!
