Dale Watson
Commercial Agriculture Beef and Livestock Specialist
University of Missouri Extension

 

 

 

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Please send your comments and sund suggestions to Dale Watson, Commercial Agriculture Beef and Livestock Specialist, University of Missouri Extension, 111 N. Mason, Carrollton, MO 64633, call 660-542-1792, or send messages by e-mail to: watsond@missouri.edu.
For the Week of
October 1, 1998

Molds and Mycotoxin Need to be Remembered

An excessive amount of moisture and high humidity sets the stage for a higher than normal level of mold development in feed supplies. The development of molds in both forage and stored grain often goes unnoticed throughout the feeding process. There are various forms, color and locations of mold development. However, moisture content, temperature and high humidity provide an excellent environment for mold development within stored feeds.

There are differences in opinions relating to the effect of molds on animal production. However, there have been numerous incidences where the mold or mycotoxin levels have caused digestive, reproductive, and reduced production in the form of both growth and milk. Calves are generally more sensitive to feed contamination than adult cattle. In affected calves, some cases have revealed severe straining and prolapses. Liver damage has been associated when high levels of aflatoxin have been fed in finishing rations. Feeding high levels of aflatoxin may also reduce the immune function, resulting in susceptibility to other diseases.

Depending on the feed containing the mycotoxin, rations can usually be formulated to meet the suggested feeding levels. Forages containing mycotoxin are the hardest to work with since forages make up a large percent of the ruminant diet. For this is the reason, make sure animals are not forced to consume large portions of moldy hay.

Moldy feeds are less palatable and frequently reduce dry matter intake. The reduction in dry matter intake leads to a reduction in nutrients absorbed which in turn reduces weight gain and results in a loss in production. It is not uncommon to see a reduction in performance of 5 to 10 percent when mold is present either forages or grains in the rations. Basically as molds grow and develop they reduce energy from the feeds which in turn requires an adjustment in the ration. Dietary fat especially is reduced in feeds that contain mold.

Molds are difficult to recognize and work with in many circumstances. Moldy or musty feeds will not always contain mycotoxins that are harmful. Mold spore count frequently underestimates the amount of mold present in the feeds. Also moldy feeds may contain a level of toxin that is not detrimental to the animal consuming it.

The effects of molds and mycotoxin in feeds are highly variable. It is impossible to predict the effects that molds or mycotoxin are likely to have in an individual situation. Ruminants are less sensitive to mycotoxin than monogastric animals and are able to detoxify or transform mycotoxin to other forms which are less harmful throughout the digestion process. Decreased feed intake, production losses of 5 to 10 percent and reduced reproductive performance are the most noticeable symptoms of the presence of mold in feeds. Young and high producing individuals are the most susceptible to levels of mold or mycotoxin.

Frequently feeds that contain lower levels of molds can be diluted in ruminant rations and utilized. However, keep in mind that high levels of mold frequently cause problems especially with the reproductive system.


University of Missouri ExtensionDale's Country Trails - October 1, 1998
http://outreach.missouri.edu/agconnection/DCT/CT100198.html -- Revised: April 20, 2004
watsond
@missouri.edu