Plan ahead when purchasing hay to save money and get the right amount.

Hay is an extremely important part of your horse’s winter diet. It is an important source of calories and the internal heat of fiber fermentation helps to keep your horse warm.

In the fall, many of us are starting to think about stocking up on hay for the winter. There are many factors that will influence your purchase.

Hay Waste

Before calculating the amount of hay you will need to purchase, you should also consider how much of your hay gets wasted either from storage or by your horses. Storage waste can range from 2-40%, depending on how you store the bales. Round bales stored outside produce the most waste, as the bottom and outermost 4” layer will be exposed to moisture. Storing hay inside or covering it well can reduce the amount wasted.

Then you must consider the amount wasted by your horses as they eat. Feeding hay on the ground is a huge source of waste, as horses trample and defecate on it. Studies at the University of Minnesotahave found that using feeders significantly reduces hay waste. When feeding small square bales, the study found the following amounts of hay waste:

While purchasing feeders is an added cost, based on the price of hay and how much can be wasted without a feeder, these feeders pay for themselves in 9 to 12 months.

Researchers at Minnesota also looked at round bale feeders, testing 9 feeders and a no-feeder control. The feeders tested allowed either complete access to the hay or restricted access (slow feeders). They found the following amounts of hay waste:

Without a feeder, the herd actually consumed less hay and lost weight because so much of the hay was trampled and spoiled. The payback period for these feeders was far less than the small square bale feeders because of the huge reduction in waste compared to using no feeder.

Calculating Hay Needs

To estimate how much hay to buy, you can run a few simple calculations. We will assume that horses eat approximately 2-2.5% of their body weight in hay per day as their full ration. If your horses have higher energy needs and also receive grain meals, you can subtract the weight of grain from the 2% figure based on your horse’s weight. We will also assume that the hay season lasts from November to March, and that horses have high-quality pasture for forage during the rest of the year.

1 horse at 1100 pounds x 2% BW = 22 lbs hay per day (if you feed grain, subtract its weight from this number)

22 lbs x 150 days = 3300 lbs hay per horse

Don’t forget to account for wastage! Here, we will assume 5% storage waste because our bales are stored inside and 13% waste from feeding small square bales on the ground.

3300 lbs x 1.05 (storage waste) x 1.13 (ground waste) = 3915 lbs hay per horse

If you buy your hay by the ton, this would be 3915/2000 = almost 2 tons of 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, 3915/40 = 98 bales per horse.


Forage is the most important part of your horse’s diet, and during Pennsylvania winters, hay is the most economical way to provide forage. By planning ahead and running some simple calculations, horse owners can save money and ensure that they have purchased the right amount of hay to last through the winter.


Authors: Laura Kenny, Andrew Frankenfield

Grass hay photo by: Danielle Smarsh, PSU

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