I am going to raise some meat birds this year. I want to put them in a tractor that i can move each day - they won't have any "indoor" area and i don't want to get them too early as far as temperature is concerned. I know i'll keep the chicks indoores with 90 degree for a couple weeks, but what does the temperature need to be outdoors - at night - for it to be okay to move them outside. thanks,