Yes, if a rabbit is very underweight it can be fed Porridge but normal healthy rabbits don't need it. There are many other treats you can give your bunny which won't tend to put weight on. Usually you have to watch a rabbit's weight as they can become obese which in turn leads to many health problems. Treats you can give are Readigrass which they love, little pieces of Spring Greens, many herbs, dandelions, tiny pieces of carrot, but most of all they need hay. This keeps their teeth in good order as they are growing all the time and it is also good for their digestion. Breeders sometimes feed Porridge but a normal pet rabbit should not need it. Hope this has been of help to you.