Alfalfa is not a grass hay, it’s a legume, similar to peas or lentils. Grass and hay made from grass need a particular chewing action that helps wear the molars properly. There is no other food (except for straw) that rabbits use this chewing motion for. Alfalfa hay will not wear teeth as well as grass hay.
It’s very high in carbohydrates, protein and calcium . The fibre content is not as high as for grass hay. These factors mean that it isn’t as good as grass hay is at keeping the gut moving and also that it gives rabbits nutrients that are over and above their dietary requirements, and out of step with a ‘balanced’ diet. The calcium levels in particular are too high for adults, other than pregnant and lactating females.
It’s something that only youngsters or pregnant and lactating females should have, and not on a regular basis or in any great amount.
We aren’t saying don’t feed it, but your rabbits, even youngsters, shouldn’t have it as a replacement for grass hay, but rather as a supplement to grass hay (or grass) which should be available at all times. A small handful 3-4 times a week is plenty. They should also have dark green leafy veg as part of their diet from weaning onwards – in the wild they would begin nibbling greens before weaning is complete, and this is what millions of years of evolution has made their gut suited to – and unlike wild rabbits, because we want to be sure they get the best possible diet with no nutrients missing, they should have some extruded pellets also, following the instructions on the product packaging.