I have a thought about how this mix of cartoony and realistic could work better, at least for those of us who are skeptics (myself included)...
What if you actually tried to make it look like realistic *cardboard cutout cows*? I think if you look closely at the current textures they imply that this is just a cardboard creation (you see a cardboard edge I believe). But it's just a texture, and the smooth surface and other details make it look truly cartoony. But if you worked on a semi-rough "paper" texture/bump, with the same color texture, and made the model more detailed depicting individual sheets of cardboard, and the modeled the way such a cow "cardboard sculpture" might appear in reality...
Then you have your amusing, surreal element, but it also fits with the realistic background. Just a thought.
- Oshyan