Use D3. On the mice--it's an interesting question. Food data bases just give us cholesterol content of food--I wonder if 7-dehydrocholesterol is high in those foods that are a bit higher in cholesterol, like eggs, shrimp, liver etc. I don't know if mice specifically are higher in 7-dehydrocholesterol than other animals, just that the paper mentioned that the natural diet of cats of mice etc. would be rich enough in this nutrient to provide enough precursor to prevent rickets.