My daughter is getting 4 ducklings this week. I want to take care of them correctly. I need to know how long to keep them under a heat lamp? Also I have game bird starter. That is what I was told to feed the last ones that we lost. It is upper 20% protien. do I need to switch to a grower & if so at what age? Any help would be great. Thank you very much for all you help in advance.