I don't know where that # came from but it might be for a gallon (dry) measurement. Fat (oils) are the most calorie dense food out there at 4000 cals (4 mCal) per pound.
I thought it sounded high which was why I asked if anyone knew - deserthorsewoman kindly replied
Hay prices seem to differ from place to place and here in CT its sold by the bale even when you buy in a large quantity - and I've bought from 3 different main suppliers now
Its hard to know how many square bales are in a ton because they all differ in size but if you go from anything between 33 and 50 bales in a ton it costs me between $350 to $231 based on $7 a square bale for reasonable quality hay that they'll eat and not trash around the field or stable