2020 Fall Feedstuffs Reminders

This fall and winter, cattle producers in NW Iowa will be dealing primarily with drought-stressed feedstuffs, which present their own set of challenges.
 
Water– streams are running very slow, if at all, and ponds are stagnant.  Both are ideal conditions for the development of blue-green algae.  This algae produces toxins affecting the nervous system and liver and can be deadly if consumed. Clean water is a MUST for cattle.  A word of caution – make sure the tank used to haul water does not have pesticide residue in it.   
 
Regular Hay– early rains delayed harvest of the first crop for many producers, and drought has affected recent cuttings.  In both cases, the hay may contain more lignin and not be as digestible.  It will be important to sample this hay and send it to a commercial laboratory for nutrient analysis.  More than likely, it will be lower in energy and protein.  Supplementation with corn will help balance the energy, and adding distillers grains to the ration will provide extra protein.
 
CRP Hay– book values for energy and protein would suggest that the nutrition of CRP hay is similar to cornstalk bales, which is very low.  Hence, supplemental energy, protein and vitamins and minerals will be needed.
 
Corn Silage– don’t get in a hurry to open up your silage piles!  Much of the corn this year has a developed ear, but not all.  Development of the ear is important as it serves as a sink for nitrates to be converted to crude protein.  If you had fields with underdeveloped ears, there is the possibility that the silage may contain higher levels of nitrate, which can be toxic to cattle.  The good news is that if the silage you chopped had high nitrates levels, four-to-five weeks of proper fermentation can reduce the nitrate levels up to 40%.  Plan to test drought-affected silage for nitrate level prior to feeding and dilute with low nitrate feeds, if needed.  Yes, there is a cost for the laboratory analysis, but this minimal compared to having a dead animal!     
 
Grazing cornstalks– cattle grazing cornstalks are not at as high of a risk for nitrates because they will select the nubbins, leaves and shucks which have low nitrate levels.  Plan to move the cattle to a new field when they have cleaned up these plant parts and do NOT force them to eat the stalks.  Stalks will contain the highest levels of nitrates.
 
Another caution – before turning cattle into a cornstalk field, check for piles of corn on the ground and the amount of ears that dropped.  With drought this year, the stalks were not as strong and even minor winds caused some lodging.  If there is a lot of corn remaining after combining, there are two alternatives – limit the area that will be grazed daily with cross-fencing or limit the amount of time the cattle are allowed to graze daily.  Feeding them hay prior to turning them out to graze will also help prevent overconsumption. 
 
Corn – Blue-eye mold, which is a blue line down the center of the corn germ, was reported in old crop corn.  Elevators and corn processing plants may discount this corn as damaged.  If blue-eye mold is apparent, send a sample to a commercial lab to test for mycotoxins.
 
Drought-stressed, new crop corn has its own issues – test weight, mold and the potential development of mycotoxins.  Research would suggest that light test weight corn will not store more than a couple of months, so plan on feeding it first.  For feedlot cattle, corn with a test weight in the high 40’s will likely be within the 95% of the feeding value of normal corn; whereas, corn in the high 30’s to low 40’s will be within 90% of normal feeding value. 
 
With any feed, the presence or absence of visible mold is not a good indicator of whether mycotoxins are or are not present.  But, drought-stressed, new crop corn will be more prone to aflatoxin, vomitoxin, fumonisin and other mycotoxins.  There is a basic mycotoxin test that can determine what mycotoxins are present and their level.
 
Last, but not least – for your protection, it is advisable to wear a mask when handling corn containing molds and mycotoxins.
 
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Beth Ellen Doran, Beef Field Specialist

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