I havent been able to get anty of mine to breed since the weather has turned colder, but have increased the amount of oats I give. I generally feed my mix of food every other day apart from heavily pregnant and nursing does and under 8 weeks but I am now feeding plain oats instead of having the day without food. Mice do surprisingly well in the cold, I;ve just been out to the shed and they are all running around like loons, I thought they would be hiding in thier nests.