During periods of extreme cold when food availability is not an issue, hypothermia is likely to set in before appreciable weight is lost. If something is wrong with the food, then they may not be as interested in consuming it.
I suggest switching diet over to a flock raiser with more protein. Have free-choice oyster shell on the side to meet calcium needs proportional egg production. The corn on BOSS they have to work for can be used as a measure of how much more they want to eat.
Birds being partial to corn and BOSS is typical, especially when it is cold. Your temperatures are cooler than mine ever get although my birds almost certainly must work harder to get their eats and mine are likely exposed to more windchill, especially at night.
I suggest switching diet over to a flock raiser with more protein. Have free-choice oyster shell on the side to meet calcium needs proportional egg production. The corn on BOSS they have to work for can be used as a measure of how much more they want to eat.
Birds being partial to corn and BOSS is typical, especially when it is cold. Your temperatures are cooler than mine ever get although my birds almost certainly must work harder to get their eats and mine are likely exposed to more windchill, especially at night.
