The moisture content of stored hay can affect the quality of the livestock feed and how well it can be stored. High-moisture hay is prone to forming mold, which leads to an overall loss of feed quality. This can be particularly dangerous in hay fed to horses, which have little tolerance for mold dust. Some other species of farm animals do have a higher tolerance for the hay dust but will still suffer from the lower quality of feed.
Moisture Testing Equipment
For large-scale operations, electronic moisture testing equipment is available. These devices are as simple as a probe and control unit and provide an almost instantaneous reading.
Some operations, usually commercial hay sellers, need to provide certified information as to the quality of their hay. These farms might submit the hay to a commercial lab for testing.
For smaller farms, moisture testing procedures using standard kitchen appliances have been developed. Although they are not as accurate as laboratory or electronic tests, they do give the farmer useful information.
Home Moisture Testing
According to the University of Manitoba, testing the moisture content of hay can be accomplished with a home microwave.
The farmer should select a representative sample and cut the hay into one-quarter to one-half inch pieces. Weigh out 100 grams of the hay sample with a kitchen scale. Other weights can be used, but 100 grams will simplify the math of calculating the moisture content.
The sample is placed on a paper plate and microwaved for three to four minutes, along with a small glass of water to prevent fire in the microwave. At the end of the cycle, remove and weigh the hay before returning it to the microwave for one more minute.
The weight loss of the hay represents the moisture evaporated out of the hay. The microwaving and weighing cycle is repeated until the weight remains constant from cycle to cycle. This indicates all the moisture has been removed from the hay. At this point, if the process started with 100 grams of hay, the difference in the weight between the dried hay and 100 grams is the percentage moisture content of the original hay.
If the testing started with something other than 100 grams of hay, the formula for determining the moisture content is the original weight minus the final weight divided by the original weight times 100.
When to Moisture Test Hay
The best time to moisture test hay is just before baling or loose stacking is planned. The idea is to determine if the hay is at the right moisture content for storage before it is baled.
Also, caution is suggested during microwaving to make sure the hay doesn't burn. The fire could damage the microwave, and the smell of burnt hay is likely to linger for a long time.