University of Maryland Extension

Calculating Your Horse's Winter Hay Needs

Author: 
Erika Crowl

Colder months are upon us and now is the time to be stocking up on your hay supply for your horses. As the temperatures start to drop below freezing, pasture grasses will begin to reduce their growth and horses will need to rely on other sources of energy to maintain their body temperature. A greater amount of heat is produced through forage utilization because of the higher fiber content. Fiber is utilized through bacterial fermentation within the cecum and large intestine. Significantly more heat is produced in bacterial fiber fermentation than in digestion and absorption of nutrients within the small intestine where grains are broken down. 

When calculating how much hay you will need, you should also take into consideration the amount of hay that will be wasted from either your horses or storage. Surprisingly, storage waste can be up to 40% depending on forage type, storage method, environment, and storage length. Hay stored outside tends to be the most common practice, but outdoor storage waste ranges from 5-35% depending on the amount of rain or snow the bottom and outermost layers  are exposed. If you can store hay inside, you can potentially reduce hay waste by about two-thirds. 

Researchers at University of Minnesota published two separate studies on the amount of hay wasted by your horse. The studies focused on hay waste, estimated hay intake, herd bodyweight change, and payback with small square bale feeders and round-bale feeders. 

When feeding small square bales, the study found the following amounts of hay waste and hay intake:

Feeder TypeHay Waste, %Hay Intake, %BW
Basket32.4
Hayrack52.4
Slat12.2
No Feeder132.2

When using a round-bale feeder or no-feeder, they found the following amounts of hay waste hay intake: 

Feeder TypeHay Waste,%Hay Intake, %BW
Restricted Access Feeders5-112.3-2.4
Circular, Free Choice Feeders13-332.0-2.2
No Feeder571.3

To see the full results of “Selecting a small square-bale feeder” visit, https://extension.umn.edu/horse-nutrition/selecting-small-square-bale-feeder 

To see the full results of “Feeding Horses with a round-bale feeder” visit, https://extension.umn.edu/horse-nutrition/feeding-horses-round-bale-feeder

Now, that you have taken hay waste into consideration you are ready to calculate how much hay you will need to buy this winter. Horses should consume 2% of their body weight in hay. For example, a mature 1,000 pound horse should consume 20 pounds of hay per day. Some horses have higher energy requirements and require extra supplementation with grain during these months. It’s important to pay close attention to body condition during these periods, and actually “feel” your horse as their winter hair coat or blanket can give you a false sense of body score.  

For a quick calculation, we will assume your horse weighs 1,000 pounds and are feeding hay from December 1- March 31 (121 days):

1 horse at 1000 pounds x 2% BW = 20 lbs hay per day 

20 lbs x 121 days = 2,420 lbs hay per horse

Now, you need to account for hay waste.We will assume 5% storage waste because our bales are stored inside and 5% waste from feeding small square bales in a hayrack feeder.

 2,420 lbs x 1.05 (storage waste) x 1.05 (ground waste) = 2,668 lbs hay per horse

 If you buy your hay by the bale, you will need to find out the approximate weight of each bale. Assuming a 40 lb bale, 2,668/40 = 67 bales per horse will cover 121 days.

With a few simple calculations you will be able to save some money and be prepared for the winter months to come. For more information or advice, contact your local extension agent. 

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