Flush feeding before breeding makes up for 10 days of feeding just to maintain body weight. After the first few days of life, the next critical time is just after weaning. The major problems are E. coli diarrhea swine dysentery, manage and ascariasis. Ideally piglets are mixed a few days before weaning and left in the crate a few days after the sow leaves. Convective loss is determined by air temperature and movement, radiation loss is largely from wall and ceiling temperatures.
Insulation is important.