I feed adult boas 6 feet and over on appropriately sized rabbits every 10 days. Before that size I use one or two of the largest rats I can get my hands on. We'll often switch up and feed rabbit for awhile then offer a rat or two for a feeding then back to rabbits. The boas seem to respond nicely to the change up in prey once in awhile (but then most BCI's seem to eat just about anything that wanders in front of their hungry jaws LOL).

Remember though if you decide to feed rabbits that you need to find a meat rabbit breeder. Not all breeds of rabbits make good feeders. Meat breeds are obviously meatier. Fancy breeds are bred for pets and tend to be less meat, more fancy fur and so forth. I get our meat rabbits for boa feeding from a breeder that is breeding meat rabbits for human consumption.

Also remember that when you size a rabbit it's different than a rat. Rats are basically cone shaped with the largest part of the rat being it's butt and hips. With rabbits it's their big round heads that are the largest bit for the snake to swallow. It's sort of this way - rabbits are larger than they appear - so go smaller rather than larger if in doubt on size.