Hello MadDogs89 and welcome to the forum!
Regarding a comparison between the food she was eating, namely Skinner's Field and Trial Duck and Rice (SKINNERS), and the alternative foods of James Wellbeloved adult Duck (JWB), and Arden Grange adult lamb (AG), it sounds as though your vet may be suggesting to continue feeding a food with only 1 named meat protein, be that either lamb or duck, which makes sense as this gives a lesser possibility of a further inflammatory reaction; rather this than ‘risking’ at this stage a food with multiple meats, and moreso in particular avoiding any unnamed meats.
All of those foods mentioned are reviewed in the allaboutdogfood Dog Food Directory together with their nutrient profiles which makes it easier to compare the nutrients of each of the foods. SKINNERS nutrients
of protein are in the lower average range of protein with a level of 23.9, with a low average fat 11.4, mid high average fibre 3.3, high average ash 9.6, and high above average carbohydrate 54.
Comparatively JWB nutrients
are borderline average protein of 21.7, low average fat 12, high average fibre 3.8, below average ash 5.4, high above average carbohydrate 54.9. AG nutrients
are mid average protein of 27.2, high average fat 16.3, borderline average fibre 2.7, borderline average ash 7.6, and high above average carbohydrate 46.2.
Of these 3 foods there is a difference in the levels of the nutrients between SKINNERS and JWB and AG and though the numbers themselves don’t seem to be that different, when worked out as a percentage there are some nutrients which differ greatly as shown in the following table:
SKINNERS & JWB
SKINNERS & AG
For dogs with IBD, as David writes here in another of his excellent articles Prescription Veterinary Diets
you’d want to be feeding a diet of low fat, which is highly digestible, hypoallergenic, high fibre and if the IBD was caused by eating gluten then it’s best to avoid gluten.