When they say your pigs diet should be 0.3% calcium does that mean 0.3% of the calories they consume? Or 0.3% of the food they consume in grams/ kilos?

This site:
https://www.nap.edu/read/4758/chapter/6

Says 8 grams of calcium per kilo of feed. But if you calculate for how much a pig eats in grams a day this has your pig eating 1,000 + mg of calcium daily (don?t have the exact number in front of me just now). More than the human amount! So this cannot be right

But if I calculate for how many calories they eat in a day (I read an adult eats 91 calories a day. Correct me if this is wrong) x 0.3% = 0.273 g = 237mg. This sounds MUCH more normal for a small animal.

Then if 70% of their diet is hay, 70% of their calcium should come from hay (right?). 273mg x 70% = 191 mg of calcium that can come from their hay a day. Then then the remaining 82mg should come from fruits and veggies/ pellets during day then. I am not feeding any pellets so all would have to come from veggies/ herb/ flower forages etc keeping to a good Calcium to Phosphorous ratio.

Any thoughts on this? Does this sound right?

Thank you!