I notice there is a lot of discussion on what substrate to use in the brooder, i haven't seen dirt as an option much. My first chicks were hen raised and straight out on to dirt, with cane sugar mulch in the nesting box. This lot are hand reared. They are 4 days old. I have them on cane sugar mulch, but i just dumped a bowl of dirt in there and they went nuts! Is there any reason too not raise them on dirt? Maybe the mulch under the heat where they like to sleep?