Leaves contain two-thirds of the protein, 90 percent of the vitamins and 75 percent of the total digestible nutrients (TDN) in alfalfa hay. In producing high-quality alfalfa hay, the emphasis should be placed on retaining as many leaves as possible.
New Mexico State University research demonstrated that 30 percent of the leaves were lost when alfalfa was baled at 15 percent moisture.
In another trial, NMSU found that the most significant protein loss occurred when alfalfa hay dries down from 23 percent to 13 percent moisture. Most universities recommend baling alfalfa hay between 15 percent and 20 percent moisture (wet basis) for maximum quality.
Getting alfalfa off the field as soon as possible is very important. If cut alfalfa is left in the field too long to dry, nutrients are lost, and the quality of the hay deteriorates rapidly. This is true even in areas where rains are not common during the hay harvest season.
Other good reasons for baling at higher moisture levels:
- Reduces chance of rain damage to the cut crop
- Longer baling day – start earlier, stay later
- Reduces wheel damage and windrow shading to the plant re-growth
- If irrigating, helps get water back on the crop sooner
- Increases harvested tons per acre – more leaves
When making large square bales of high-moisture alfalfa hay, two important factors must be considered to keep hay from excessive heating, browning and spoiling due to mold.
Knowing the total moisture of the hay at baling time is the most important factor to be considered. You need the best technology available to help you determine it; you cannot guess and be sure.
The second factor is to protect the hay in storage. If the moisture is above 15 percent, you need to add a preservative to stop mold growth.
Electronic moisture meters
Electronic moisture testers have been used in the hay industry for over 30 years. These probe-type moisture meters (both hand-held and on-baler systems) operate on the principle of electrical conductance.
As electrical current flows through the bale from one contact point to the other, the ions (mineral salts) within the water conduct the electricity to generate the moisture reading.
The higher the ion level within the water, the higher the moisture reading will be. They measure stem moisture less accurately than dew moisture.
With this system, the accuracy of moisture prediction also depends on:
- Type of forage
- Bale density
- Number of probe readings per bale
- Depth of probe reading
- Whether acid preservative was applied
Depending on the circumstance, the typical error for this type of moisture measurement can be as much as 5 percent.
Microwave moisture meter
Microwave technology comes from the mining and cotton industries, where accurate moisture readings are essential. For 10 years, Australia has been using microwave technology to measure moisture in large square bales.
It is also available in the U.S. for use on large square balers.
Microwave technology has been adapted to mount on the bale chamber and calibrate the moisture from one end of the bale to the other. A microwave antenna is mounted on each side of the bale chamber.
As the bale passes between the antennae, the microwave signal picks up the molecules of water it detected. The reading consists of water found both inside and outside the stem (total moisture). The typical margin of error is 0.5 percent based on an oven-dried sample in a laboratory.
The accuracy of microwave technology is documented by laboratory tests performed on hay samples during the last 10 years in Australia. In addition, a grass hay trial conducted by North Carolina State University and several corn fodder trials conducted by Iowa State University during the last three years have proven the accuracy of the microwave system.
This system is also capable of marking spots of high moisture on the bale with paint so the stacker can readily identify high-moisture bales and handle them with proper caution. Producer Keith Phillips of Missouri says, “We take two trailers to the field to pick up bales.
The painted bales go on one trailer, and the unmarked bales go on another. It allows us to segregate the bales with damp spots. The marking system makes it easy for my hired help to determine which bales go to the drying shed.”
Since the initial cost of the microwave moisture meter is slightly higher than the electronic on-baler system, you should compare the benefits of both before you make a purchase.
Use of preservatives with hay moisture challenges
There are presently several hay preservatives available designed for use in high-moisture hay. Research reports show that organic acids, sulfur compounds and certain bacterial inoculants stop plant respiration and promote faster curing.
These preservatives are applied to the hay as it enters the baler.
On occasion, hay does not seem to dry fast enough to avoid approaching adverse weather. In this circumstance, using a preservative allows hay to be baled at higher moisture levels.
Using preservatives also permits baling earlier in the morning and later into the evening when dew moisture would normally halt the baling process. Often baling can begin a day or two earlier.
Producer Jim Foss of Oregon uses a high-quality preservative and says, “On my third cutting, I baled some hay all the way up to 19 percent moisture. It was the best hay I ever made.
By using my preservative I was able to put up hay two to three days earlier. I could get the water back on the field sooner.”
Research with preservatives at several Midwestern and Eastern universities shows that higher-moisture alfalfa hay treated uniformly with an adequate amount of chemical preservative yielded up to 300 more pounds per acre than field-dried hay.
The increase in yield was due to less field leaf shatter and less exposure to adverse weather.
After two months storage at New Mexico State University, treated hay had better color, higher percentage of leaves, less dust and less mildew and odor than conventionally baled hay.
Use a preservative that is effective against mold
Baled hay naturally contains millions of bacteria and mold fungi. Mold will grow on hay without a preservative at moisture levels above 14 percent to 15 percent.
The mold growth produces heat and can result in large amounts of dry matter and TDN loss – a loss of carbohydrates and binding of proteins.
Two types of preservatives have been proven to be effective against mold growth and are available for use on high-moisture baled hay: organic acids and sulfur compounds.
To be effective, organic acids need to be used at a higher rate (as much as five times more) than the sulfite-based products due to the difference in their mode of action.
Acid products are also a challenge to handle due to their strong odor; sulfite-based products are more user-friendly.
Performance results in dairy cows
Utah State University conducted a lactating dairy cow trial comparing the difference in milk production when feeding sulfite-treated hay, acid-treated hay, inoculant-treated hay and field-dried low-moisture hay. All hay was baled in the same field.
Cows fed sulfite-treated hay averaged over 2 pounds more milk per day than cows fed either acid-treated hay or inoculant-treated hay. Compared to field-dried low-moisture hay, sulfite-treated hay produced over 6 pounds more milk per cow per day.
All treatments showed higher milk production than untreated low- moisture hay. However, there were no significant differences in feed intake among treatments. FG
Earl Kennel
Forage Quality Consultant
International Stock Food
