Mine did very well on timothy hay cubes, but those are hard to find where I live. Usually when I don't have hay cubes I don't provide hay except for stressful situations (show, breeding, nursing, weaning, illness, transport, etc). I mix purina show, purina complete, BOSS, calf manna, and oats for my feed. If you don't want to feed hay, find a line of rabbits that has been raised and bred on a diet without much hay (so that the ones selected for breeding were ones that did well on that diet) and find a good, balanced diet (whats available and good varies with location, so ask around you). If you do decide to use the hay pellets, I wouldn't reduce the amount of normal pellets though, while you were testing it out.