How much hay do you need for this winter? The answer to this question depends on several factors. How long do you expect to feed hay? How big are the cows? Are the cows lactating or not? How much hay will be lost because of storage and feeding losses?
First, it is important to think in terms of pounds of hay and not just the number of bales. The weight of a bale will vary tremendously depending on size and density. For round bales, it is important to consider the width and height (diameter). The width should be expressed first, followed by the height. Below is a list of round bale sizes, their calculated volume, and their estimated weight assuming a constant density of 11.21 pounds per cubic foot. As the example shows, a 4X6 bale is larger than a 5X5 bale.
- 4X5 bale: 79 cubic feet = 880 pounds
- 4X6 bale: 113 cubic feet = 1,267 pounds
- 5X5 bale: 98 cubic feet = 1,100 pounds
- 5X6 bale: 141 cubic feet = 1,584 pounds
Density of a bale can be influenced by tightness of wrap, forage species, forage maturity, and other factors. Tightness of wrap will vary depending on operator preference and the equipment being used. A bale of the same size can easily vary by 200 to 300 pounds because of differences in density.
More information on bale weight, value and transportation considerations can be found in the publication “Bale weight: how important is it?” from the Texas A&M AgriLife Extension.
On a dry matter basis, a non-lactating cow will generally consume about 1.8% to 2% of her weight of moderate-quality hay. A lactating cow will consume about 2.3% to 2.5% of her weight of the same hay. Hay contains some moisture; in the examples below the assumption will be made that hay is 90% dry and contains 10% moisture.
- 1,100-pound cow x 2.5% intake ÷ 0.9 dry matter = 30.6 pounds per day
- 1,300-pound cow x 2.5% intake ÷ 0.9 dry matter = 36.1 pounds per day
The amounts above should be increased for storage and feeding losses.
Many extension services have spreadsheets and other tools to help calculate hay needs based on cow weight, intake, storage losses, feeding losses and length of the feeding period.
