Calculating Winter Hay Supply

Weekly News Article for The News-Democrat, Carrollton, KY

(Photo by Stephen Patton, University of Kentucky)

October is an important time for livestock producers to assess their winter hay supplies.  With the majority of this year's hay made, now is the time to determine whether you have enough to get your animals through the winter.

Determining this amount is a rather straightforward task.  Here is how to get a fairly accurate estimate:

1. Estimate the number of days you will feed hay this winter.  In a normal year, Kentucky producers average 120 days (from December 1 to March 31) of feeding hay.  This will vary depending upon your situation.
2. Determine the amount of feed your animals will consume each day.  Cattle and horses consume an average of 2.5 percent of their body weight every day.  To determine this amount, multiply the average animal's weight times 0.025 (2.5 percent).  Multiply that answer by the number of animals you plan to feed.
3. Multiply the products of #1 and #2 together.  This will give you a good idea of the approximate pounds of hay you will need for the winter.
4. Take three or four hay bales to a facility with a scale, such as the local feed store, if possible.  Take the bales' average weight and multiply that by the number of bales you have.  Compare this number to the amount you need.
5. You also need to allow for storage and feeding loss, and adjust your hay supplies to cover these losses.  If you store your hay outside, your losses may be more than 50 percent.  A 50 percent loss would mean that you need to double the amount of hay you calculated, in order to feed your animals.

To help with deciding storage loss, use the following estimations:

Storage - Loss, %
Inside on rock - 3 to 5
Inside on ground - 5 to 7
Outside covered on stone - 10 to 17
Outside covered on ground - 15 to 35
Outside uncovered on stone - 13 to 20
Outside uncovered on ground - 20 to 35

Let's do an example, putting the above steps in play...

In my theoretical situation, I've got 35 cows, and their average weight is 1300 pounds.

Step 1:  Estimate the number of days I will feed hay this winter.

I'm going to stick with the average of 120 days.  (Next year, I'll try rotational grazing so I can extend the grazing season and shorten the days I feed hay.  I've learned my lesson this year.)

Step 2:  Determine the amount of feed your animals will consume each day.

Multiply 2.5% by the body weight...
0.025 x 1300 lbs = 32.5 lbs

Multiply the above product by the number of cows I'll be feeding...
32.5 lbs x 35 cows = 1137.5 lbs

Step 3:  Multiply the products of #1 and #2.

120 days x 1137.5 lbs = 136,500 lbs of hay needed for the winter

Step 4:  Determine how much hay I have on hand.

I've estimated the average weight of my round bales to be 1200 lbs and I've got 120 bales, so...
1200 lbs x 120 bales = 144,000 lbs of hay on hand

Now, comparing it to the number I calculated in Step 3...
144,000 lbs - 136,500 lbs = 7,500 lbs of surplus hay

Looks like I should be fine, but wait, I need to account for potential loss.

Step 5:  Account for storage and feeding losses.

For this example, I'll say I store my hay inside, on the ground.  According to the above storage loss estimation chart, the loss is 5-7%.  I'll account for 7%.  For feeding loss, I'll estimate 10%.  Therefore, I'll need to take a total of 17% off of the hay on hand to account for potential loss.

144,000 lbs x 0.17 = 24,480 lbs of estimated hay loss
144,000 lbs - 24,480 lbs = 119,520 lbs of hay available to feed

Comparing that estimation to how much hay I need...
119,520 lbs - 136,500 lbs = -16,980 lbs

Therefore, I'm lacking 16,980 lbs of hay to feed my 35 cows for 120 days through the winter.

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Before feeding hay, have it tested for nutrient content and toxins.  The Kentucky Department of Agriculture's (KDA) Forage Testing Program can help you determine if your animals are truly getting the nutrition they need or if you need to supplement the ration to maintain your animals' body condition.  You can reach the KDA at 1-800-248-4628.

A one-two punch of overgrazing in many fields during the 2010 drought, followed by an extremely wet 2011, resulted in johnsongrass taking hold in pastures where it has never been before in 2012.  A warm-season annual, johnsongrass has the potential to cause cyanide poisoning in ruminants.

Make sure hay coming from a field containing johnsongrass is completely dry before feeding it to your animals.  Thorough drying will allow any potential cyanide threat to dissipate.

If you want to use a field with johnsongrass for grazing, wait at least two weeks after a light frost, three days after a killing frost, or until the johnsongrass is completely dry before you allow the animals to graze the field.