Well, it’s not recommended that you give your rabbit any greens until they’re at least 4 months of age or older. If you give it to them while they’re young, it may cause enteritis (diarrhea), which is a serious killer of rabbits that are under 4 months. However, once they are beyond this age you can begin to feed them greens, a little at a time, keeping a close eye on them in case the broccoli threatens to cause more gas than their systems can handle. They will begin to adjust to the food, but it should still be given to them only in moderation. Even beyond the four month mark, their main diet should be water, hay, and pellets made especially for your little bunny.
If you choose to feed them broccoli, it should be as part of a mixture with other vegetables (for example, lettuce and cauliflower). Rinse the veggies and leave some water on them, as this will help with digestion. As long as you’re starting your rabbit on broccoli slowly, they won’t only begin to more easily digest it, but they’ll often come to love it. In fact, you’ll probably find it’s the first thing they pull out of their dish!