Many farmers are taking their last cutting of hay off for this year, so now would be a good time to review some steps in helping to preserve the hay during the winter months. 

Hay is the most commonly used stored feed on livestock farms across the nation. Unfortunately, losses of hay during storage and feeding are often high. It is estimated that the total value of hay storage and feeding losses nationwide exceeds three billion dollars annually!

Good hay quality starts at harvest. Hay that is baled at moisture contents greater than 20 percent can develop mold and lose dry matter and quality to bacterial degradation.

In rare cases, hay baled at a high moisture content can spontaneously heat or combust. Moldy hay can be detrimental to livestock health.

The extent and duration of temperature rise in hay depends on moisture content. All hay baled at moisture contents between 15 and 20 percent will undergo some elevation in temperature in the first 2 to 3 weeks after baling. 

This heat buildup is referred to as “sweating” and is due to plant respiration and microbial activity. This temperature increase continues for up to 10 days. At a moisture level of about 30 percent, a bale may maintain a higher temperature for up to 40 days regardless of the forage species or bale shape.

Temperatures can range from 130 to 140 °F during the initial stage and decrease to 60 °F after 40 days. If temperature increase is no greater than 130 °F, then the hay should suffer no great reductions in hay dry matter (DM) and quality. 

However, during the sweat, measurable losses of 4 to 5 percent in hay DM may be recorded. Once stored hay has reached moisture equilibrium, there will be a 1 percent DM loss for every 1 percent loss in the original field baling moisture. For example, if hay was originally baled at 20 percent moisture and after 3 weeks reaches 12 percent moisture there should be a corresponding 8 percent DM loss.

Maintaining hay quality after harvest depends on proper storage. Total loss for high quality hay stored outside on the ground could be 25 percent to 30 percent, while losses for animal feeding could reach 40 percent. This dry matter loss from poorly stored hay also translates to significant dollar losses when lost nutrients have to be replaced by protein or energy products.

The amount of storage losses are directly related to several factors:  Moisture content at baling and the time of storage, Storage conditions (outdoor vs. indoor), Environmental conditions (relative humidity, air temperature, and air movement), and Forage species.  

It is important to store bales in a well-drained area. Most storage losses occur where hay bales touch soil. Place round bales on gravel, pallets, or tires to minimize dry matter losses. Elevation is not necessary for bales covered in solid plastic because the plastic layer provides a barrier against moisture movement from the soil. Some studies have shown that these techniques reduce storage losses by 15 percent.

These are the not the most recommended methods, but they are the ones most frequently used by producers with limited storage capacity. These methods are recommended only if the storage period is shorter than 90 days and daily temperatures are lower than 95°F. In this case, use a tarp to protect hay from the weather, which reduces dry matter and hay quality. When using a tarp to cover hay bales, stack hay in a pyramid formation. Do not place the plastic underneath the bales because water could pool inside the tarp. 

Hay can also be stored in enclosed barns or roofed, open buildings, also called pole barns, but the cost of the structure can increase the cost of hay storage considerably. 

Return on investment could take several years, depending on the cost of the structure and hay prices.

Hay losses also occur during feeding and can be a major expense in livestock operations. Hay losses are greatest when several days’ worth of hay is fed at one time. Feeding a one-day supply of hay each day minimizes waste but increases labor costs.

Although feeding losses cannot be eliminated, there are ways to reduce the amount of hay lost.

Using hay feeders such as cone, ring, trailer and cradle feeders can reduce losses by preventing cattle from trampling or bedding down in hay. Cone feeders are the most feed-efficient type, but many producers use ring feeders instead because they are less expensive.

Many producers distribute the bales on the ground as loose hay or deposit it in a windrow for feeding. These feeding methods are labor intensive and can result in high trampling and soiling losses if too much hay is fed at one time. If a 3-day supply is unrolled, feeding losses could be up to 40 percent or more. 

If fed on a daily basis, feeding losses could be reduced to 12 percent.

One advantage of this system is that feeding areas vary, allowing for better manure and nutrient distribution. Feeding in areas with thin, poor soil is ideal in this case because manure builds hummus and mineral deposits in the soil.

Some producers might think that hay losses are unimportant, but hay losses can add up to significant amounts of money, especially where drought affects available forage and hay prices.

Average hay storage and feeding losses could account for over 10 percent of livestock production costs. Producers often do not realize how large hay losses are or how easy and inexpensive it can be to reduce losses. Here’s an example: assume that a rancher has a herd of 300 cows, and their average weight is 1,000 pounds. Each cow consumes 2 percent of its body weight per day, on average, for 180 days during the winter.

 The rancher will need 635 tons of hay with 85% dry matter.

If the hay is properly stored and storage/feeding losses are 5 percent, then approximately 668 tons of hay will need to be harvested or purchased. If, however, the bales are left exposed outside on the ground, resulting in a 35 percent storage loss, then the rancher will need 977 tons of hay. 

If hay was priced at $120/ton, the additional 341 tons required due to 35% losses would cost the rancher an extra $40,920.

So, to reduce your input costs and increase your profitability, pay close attention to how you harvest, store and feed your hay this winter. As illustrated in this article, a little bit of extra management on your part can have a big effect on your bottom line.

Source: Hay Storage: Dry Matter Losses and Quality Changes, Dr. Rocky Lemus, Assistant Extension Professor, Plant and Soil Sciences, MSU Extension