Prey model (my preference) is based on what a wild dog/wolf would eat in the wild - based on a carnivore, not an ominivore.
The BARF diet is much more complicated and involves a lot of work and can be too much for some people to get their head around. The barf diet involves feeding raw meat but also, mashed veggies and grains, yoghurt, cottage cheese etc
The prey model is based around providing nutrition through raw meaty bones, offal etc alone. You will achieve balance over time by trying to feed as much of an animal as possible but there is no blending veg, grains etc as there is in the barf diet. You simply feed the raw food as is, simple as that.
I feed mine a prey model/raw meaty bones diet and here is an example.
Feeding lamb over a week.
Day 1 a whole lambs neck
Day2 a lambs shoulder
Day3 lamb flank
Day4 lamb meat mince followed by free lambs spine part of bone from butcher
Day5 lambs leg
Day6 lambs tripe and a bone
Day7 lambs liver and kidney plus a lamb bone from butcher.
it has so many health benefits and is so easy to feed.
for more information join the yahoo group called rawfeeding, also a group called rawmeatybones.
I recomend the vet Tom Lonsdales book - Work Wonders, feed you dog raw meaty bones.
The link below leads to an informative site that includes a feeding guide.
http://www.rawmeatybones.com/
I would start by giving your dog a fast day, then start by feeding raw chicken as is(you want to be feeding about 2-3% of her ideal body weight a day), just make sure that the bones you provide are raw and large enough that she has to chew it up properly to eat it.
Remember that the emphasis is on MEATY bones, not just freebies from the butcher, although they are handy for feeding alongside offal. Chicken bones are nice and soft when raw and its a fairly easy protein for them so you shouldnt have any tummy upset from a straight switch. When you first switch would keep her on the same protein for at least a week, before introducing anything else.
Remember nutrition is provided through variety over time.
If you would like any more info please have a look at the groups and the links provided,
you really are doing the best thing you can for your dog.
The site below will help dispell any myths you may have heard and also has some good meal ideas and links,
http://rawfed.com/myths/