
Hi Caileag :D
I have the opposite prob! Our boy came to us as a rescue,and was Obese for a Husky (at 15 months :rolleyes:) so we've had a delicate task of gentle reconditioning (feeding/excercise)
I'd probably err on the side of Lamb/beef than poultry for putting weight on and there's a good thread going on at the Mo about tripe,check it out.
When I first started working in a racing kennel I remember thinking; "This isnt a fun job!?? Im not out whizzing around on sleds..Im more of a 'Commi Chef'!!!" lol!!! after cleaning out kennels the vast majority of my time was spent preparing meals! and each dog had a different amount.Taught me alot!
At the moment Im half and half Barf (on seperate days!) as Im keeping weight 'down' its poultry mainly 1/2 chicken carcass or rabbit carcass.
Try these two links Im going to give you,The first one is good for you as its a useful tool for you to calculate a way to get to the ideal weight for your dog.
the second link is a calculator (all these percentages really get me

so I find this helps!)
Boneapetit feedchart you can rpint this one off too :D
And
This one if you scroll down about half way down you'll see a cartoon picture of a calculator, click on this and it will help you do the nesc. calculations for whats needed to feed your dogs body weight..or ideal body weight in your case.
Hope these help :D