Hay Fires by Mike Mehren Ph.D.

Hay Fires
by Mike Mehren Ph.D.

Hay fires aren’t exactly livestock feeding or nutrition unless you consider that the feed burned up is something that is no longer available for feeding. Earlier this spring we had a tremendous amount of rain that we needed, but unfortunately it came when some first and second cutting hay was down. It is possible that some of this hay was baled while the moisture was still dangerously high.

Hay fires may be caused by lightning strike, sparks from cigarette, or welder, or arson. However, baling when the forage is too wet causes most hay fires. The following guidelines have been established for safe moisture content:

Kind of Bales Hay	Moisture Content*
Big Bales or Round Bales	15-18%
Small bales	20-25%

*for grass or alfalfa hay.

Preservatives are not used much in the dry country, but when used, the safe baling moisture content is 25-30%. Salt is sometimes used to help control heating, however, controlled studies have shown that it is not effective. It should be noted here that some preservatives produce toxic gases when burning. Neither propionic acid nor salt
produces toxic gases.

The first 14 to 30 days after baling are when most hay fires occur. If there is any doubt about the safety of a haystack, temperature should be monitored. If a stack begins to heat, it should be moved a safe distance from anything combustible. Even year-old hay can burn if it gets wet. It doesn’t seem logical that excess moisture leads to a fire; the higher the moisture the greater chance there will be a fire. This is because microbes present in the hay start to grow and react with the hay. The table below shows some temperature guidelines to help determine whether hay is safe or dangerous.

Temperature	Comment
130 F or below	No problem
130-140 F	should be monitored every few hours
150 F	Danger, hay should be moved to provide air circulation. Check Temp. often.
175-190 F	Call the fire department.
200 F or above	Fire is present. Call the fire department.

A moisture meter does not have a long enough probe and an oral thermometer does not read much above 100 F, so neither will work for determining the temperature of a haystack.

However, a 10 ft. piece of 3/8th inch pipe with several 1/4th inch holes drilled into the side of the pipe near the sharpened end works well. A dowel can be sharpened and screwed into the end instead of just sharpening the end of the pipe. This pipe can be pushed or pounded into the center of the stack. A candy thermometer tied to a piece of string can be lowered into the pipe, and a reading taken after 10-15 minutes. Be sure to give the thermometer enough time to register. If the hay smells like caramel, tobacco, or mold there is a good chance that it is already heating. Be very careful about standing on top of a stack in this condition.

Let’s say the hay only heats to about 145 F, so no fire breaks out. There still has been considerable damage as far as feed quality is concerned. The microbes that fed on the hay have used the sugars in the hay for their source of energy. When this happens, since the sugar has been depleted, the concentration of the indigestible portion of the plant increases. The ADF and NDF will be higher. After the microbes use the sugar, if there is still enough moisture present they begin to work on the protein. This means that the protein will be lower than it was when first baled. Heating also damages the quality of the protein so that it becomes bound and isn’t available to the animals eating it. This particular kind of protein is known is Acid Detergent Insoluble Fiber –Protein (or Nitrogen, by some labs). This is a way of detecting how much protein is not available to the animals. This should not be confused with ‘by-pass’ protein. That is a form of protein that escapes the paunch, but is absorbed in the small intestine. ADIF-Protein escapes digestion all the way through the animal’s G.I. tract.

Hay that burns or has to be wet down to prevent burning isn’t suitable for feed anymore. It is best used for mulch or possibly even made into compost. When not completely burned, it is very palatable to cattle. This can fool a person into believing that cattle are getting nutrients from it. The problem is that the digestible nutrients were used up during the heating process. Trying to buy it at a discount to good quality feeder hay, usually doesn’t work. It will often have quite a bit of mold that can be toxic. The information regarding hay fires came from extension publications from the following Universities and Agricultural Ministry: Univ. Arkansas, Oklahoma State Univ. Ontario Canada Ministry of Agriculture, Univ. of Tennessee, and Univ. Virginia.

Grass seed by-products also catch fire when excess moisture is present. This has nothing to do with the following information, but seemed like a good transition at the time...
I received a copy of the “ Tall Fescue Endophyte Concepts” booklet recently. It was published by the Oregon Tall Fescue Commission. It is full of information that should interest anyone buying, selling, or feeding grass seed products. It discusses the importance of grass straw testing, and how to go about getting a good sample. It has quite a bit of detailed information about the symptoms of endophyte toxicity, as well as ways to feed an infested product without risking the health or performance of your animals. It also has information regarding endophyte testing: collecting the sample, preparing to ship, where to send the sample, and interpreting the results from the
lab. Endophyte testing is not done at feed labs. Locally, it is done at the Morrie Craig Lab, Oregon State University. The complete address is in the booklet.

You can obtain a free copy by contacting Dr. Don Ball, 120 Extension Hall, Auburn Univ. AL 36849 (Email: balldon@auburn.edu)

Michael J. Mehren, Ph.D. is a livestock nutritionist whose really great column for this month was lost in a fire near Hermiston, Oregon. He may be reached at: mehrens@eotnet.net.