I hear you Tiger, and you are correct. The reason I didn't give him numbers is because I don't know what the nutrient levels are of his other feedstuffs, the body condition of the cows, or the stage of production (gestation vs lactation). Based on these the proper feeding level of the wet gluten could be anywhere from 0 to 15#. And it's hard to give him economics without knowing what his others options (including home grown feeds) are costing.

I can say, in general, that both gluten feeds and distillers grains are a poor buy for energy relative to corn and corn silage, and an okay buy for protein relative to soybean meal.

As for a ballpark number on feeding cows, 4-8# is going to be safe, but I doubt gestating cows would need that much additional protein and he may may not be able to stay ahead of spoilage (even in the winter) if he has to take full semi loads of it.