
Hi M,
The difference tends just to be that in analysis Protein,fat,fibre and the cal:phos ratio are lower than Adult formula's.... the actual % difference varies from brand to brand.
Don't know which of the Nutro's you've got but for example here's a comparison of the Nutro Adult v Large breed
maintence formula (It was the only one I could find on the www.)
Large Breed: Adult:
Protein - 27% Protein - 28%
Fat - 14% Fat - 17%
Fibre - 2.5 Fibre - 3.0
Cal - 2.5 Cal - 1.5
Phos - 1.1 Phos - 1.4
usuable energy = 355. Kcal. Usuable energy = 369. Kcal
Does that help?
(nothing some egg and sardine etc can't top up...*if* required ;) )