Hello, my 3-week-old rabbits have poop stuck to their rears, they have started to eat pallets, alfalfa hay and green grass, they are still with their mother who gives them milk once a day. I don't know why they started pooping like that yesterday they were normal. It does not look like liquid diarrhea, it is harder and shapeless
It sounds like the beginnings of weaning enteritis, which can show up as the kits transition to eating solid foods (most often between 3-10 weeks) and their guts are not fully equipped with the proper balance of microorganisms to manage digestion. When bunnies have a belly ache and loose stools, they are sometimes reluctant to clean themselves up, which probably makes some sense, as they'd be ingesting more problems.
When this happens in our barn, the first thing we do is clean the bunnies with warm water. Only get the soiled part wet - you don't have to soak the whole rabbit, and you don't need soap. Usually just sitting their hind end in a shallow bowl of warm (not hot, of course) water for a few minutes will loosen the clump of poo, so you can clean it off gently. Don't be aggressive and pull, as the tissue in that area is very thin and tender - just let the water work and move the clump gently between two fingers until it dissolves. I wear a thin nitrile glove to do this.
Sometimes that's all it takes, and once the bunny is clean, the problem is solved. You definitely don't want to let the poo build up too much or the bunny, being plugged up and unable to eliminate its waste, will quit eating, and then you've got a much bigger problem. Keep your eye on them, as sometimes one kit will have more of a recurrent problem than others.
When we see this in our bunnies, we give them lots of hay and replace it frequently with fresh clean stuff, to prevent them from eating soiled hay. I like to put older kits on hay
only for a while, but since yours are only three weeks and still with the mother, I wouldn't pull the pellets out because the doe will need them.
I also like to give the bunnies Benebac or another probiotic, which sometimes seems to make a difference.
Honestly, though, we don't have this problem too much anymore because I tend to stop breeding does that have entire litters that get enteritis, especially more than once. It does seem to be a problem that runs in certain lines.
One thing to think about is whether you've changed anything recently - different feed, different hay, recent introduction of greens or different types of greens, anything at all. The period around weaning is pretty sensitive and a minor change in diet can have big repercussions. That's not to say you did anything wrong, it's just something to think about to figure out why the bunnies developed this problem. You may very well have changed nothing (or at least not have known it changed).