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.
I personaly always figured around 25lbs of hay per day for a average size cow when i was putting up hay. Alot of that of course they can get if pasture is available/accessable. Multiply that by your number of cows x average days you actually have to feed.
Per head daily of protein supplement should be fed along with a small amount of grain Dairy Cattle: Lactating cows:2.lbs of dry roughage daily per 100lbs of live weight. 2 to 3 lbs of concentrates per head Dairy Heifers:2 to 3 lbs of concentrates per head on good roughage. 4 to 5 lbs on poor roughage.