Because grain bread has spores in it...it does not have to wait on the fungus to grow, the spores are already in the wheat germ
Why Does Wheat Bread Grow Mold Faster Than White Bread?
When you eat mouldy bread you will get sick and you will get a stomach ache, and if you do not know what mouldy bread looks like then you should go look and find out.
Beacause weat bread have more things in it an reguler bread have milk