Whether putting food in the refrigerator, the freezer, or the cupboard, you have plenty of opportunities to prevent foodborne illnesses. One of the basics of food safety is cooking food to its proper temperature.
Re: Average hay consumption. A cow needs about 3 per cert of its body weight in roughage a day, a 1000 lb cow needs 30 lbs of hay if it has no other source of roughage.
So if she is thin, she may need to add weight as the fetus develops - about 100# of gain before she calves. So, a 1200# cow needs roughly 24# per day of hay to maintain her weight, plus another 750# of feed over the next 3 months to compensate for the fetal growth - an additional 8# of hay per day. Cows starting the winter in good condition may be fed to simply maintain their weight - and since the calf is growing inside, a static cow weight will result in a loss of condition on the cow.