How much feed do i need to make a one ton cow?

1 ton = ~2 200 lbs. Are you sure you want to "make" a one ton cow? That's a very big cow by any standards. I've yet to hear of a cow getting up to that weight, as most cows average around 1 500 lbs, more or less. Bulls get up to 2 200 lbs or more, depending on the breed. British bulls like Angus or Hereford often get up to 2 200 lbs or more, and they take more feed than a cow does.

Now as far as how much feed, this all depends on what age you are wishing to start at. A weaner heifer calf (6 months old @ ~500 lbs) gains anywhere from 0.5 to 2.5 lbs per day, with a daily intake (as-fed) between 12 and 14 lbs per day. To complicate things, her rate of intake increases as she gets older, but the rate of gain stays relatively the same throughout her growth period to maturity.

So lets make this simple scenario: you purchased a 500 lb heifer calf with a relatively stable rate of gain of 2 lbs per day with a daily intake of 13 lbs per day. So, she would reach 600 lbs in: 100 lbs/2 lbs per day = 50 days. In 50 days, in order to have gained 600 lbs (look at the previous calculation: in order to get to 600 lbs she has to gain a hundred pounds from the start: 500 lbs + 100 lbs = 600 lbs) she has consumed 50 days x 13 lbs per day = 650 lbs of feed. And so it continues to reach your target weight of one ton:

50 days to reach another 100 lbs.

Rate of intake for a 600 lb heifer = 15 lbs. 50 days x 15 lbs/day = 750 lbs of feed.

Rate of intake for a 700 lb heifer = 17 lbs. 50 days x 17 lbs/day = 850 lbs of feed.

Rate of intake for an 800 lb heifer = 19 lbs. 50 days x 19 lbs/day = 950 lbs of feed.

Rate of intake for a 900 lb heifer = 21 lbs. 50 days x 21 lbs/day = 1050 lbs of feed.

Rate of intake for a 1000 lb heifer = 23 lbs. 50 days x 23 lbs/day = 1150 lbs of feed.

Rate of intake fo a 1100 lb heifer = 25 lbs. 50 days x 25 lbs/day = 1250 lbs of feed.

Here her rate of intake starts to decrease as she has reached her target size, and now is just simply putting on fat. So, the feeding period increases to 100 days as her rate of intake has decreased from 2 lbs/day to 1 lb/day.

Rate of intake for a 1200 lb heifer/cow = 26 lbs. 100 days x 26 lbs/day = 2600 lbs of feed.

Rate of intake for a 1300 lb heifer/cow = 27 lbs. 100 days x 27 lbs/day = 2700 lbs of feed.

Rate of intake for a 1400 lb heifer/cow = 28 lbs. 100 days x 28 lbs/day = 2800 lbs of feed

Rate of intake for a 1500 lb heifer/cow = 28.5 lbs. 100 lbs x 28.5 lbs/day = 2850 lbs of feed.

In total, you are going to feed about 17,600 lbs of feed in order to get a 1,500 lb cow. The reason I stopped there is because most calculations for feed and nutrient requirement tables stop at 1500 lbs. If you are going to make a 2,200 lb cow let me advise you that you are going to make a morbidly obese cow if you keep adding more weight on her, which is not healthy for any cow of any size or breed. Therefore, should you decide to make your 2,200 lb cow, the grand total amount of feed you are going to need is 22,000 lbs.

Now this is not in a real world. In the real world you have to contend with diet changes in changes of feed associated with changes of season, weather, climate changes (drought or excess moisture), and risk of illness or infection in the heifer. These calculations do not take any of that into account; it only has isolated the number of feeding periods, the growth of the heifer and the amount of feed (of the same diet) needed to reach the projected 1 ton cow.