Challah bread Covers for Shabbot and Holidays

There are a couple of reasons why we cover the bread at the time of Kiddush.
1. As not to embarrass the bread. We usually bless on the on bread before at the start of every meal and today we are blessing on the wine first.
2. In memory of dew that covered the mann, heavily bread that dropped from the heavens while left Egypt and lived in the desert 40 years.