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December 20, 2007
Crop residues lose nutritional value with time, precipitation
WEST LAFAYETTE, Ind. - Livestock producers utilizing crop residues to feed their animals need to be aware of the decline of nutritional value to the animals and the changing nutritional need of the animals being fed, said a Purdue University expert."Given the current situation with less of a forage supply this year, many Hoosier producers have been using crop residues as a feed source this fall," said Keith Johnson, Purdue Extension forage specialist. "And that's fine, but growers need to be aware that the value of corn residues declines with each passing day and week following harvest."
Johnson said that rain and snow can cause leaching of some of the more soluble and easy to digest components in a feedstuff that is not nutrient dense to begin with. But time and weather aren't the only cause for a decline in the nutritional value of crop residues; preferential grazing plays a part, too.
"Livestock graze preferentially and eat the higher quality residues first and leave the lesser quality," Johnson said. "Nutritional value will remain more constant over time if corn residue acreage is strip grazed but this management practice is not commonly used by livestock producers."
Corn residue is a relatively low quality product. When combined with degradation, producers should be supplementing the residue by feeding more energy and protein, Johnson said.
For example, if cattle have been out in a field for 10 days, nutrition provided on the 10th day is less than on the first day, Johnson explained.
"Most cattle producers wean calves born in late winter and early spring by Nov. 1 and the nutritional need of the cow at this time is fairly low. It's a good time to use lower quality feed resources," Johnson said. "But as the needs of the cow go up, corn residues are not going to meet the nutritional needs and higher quality feedstuffs will need to be fed as the cow gets closer to calving.
"It's always important to match the forage resources available to the nutritional needs of the animal."
Johnson also encourages livestock producers feeding baled corn residues to assess how much of the residues are being consumed and how much is left in the bale ring or as bedding. Calculate the number of days available to feed livestock again if utilization of the residues is less than expected. It is important to avoid having inadequate forage supply in late winter.
More information about stretching a short forage supply and herd management tips are available at www.forageshortage.com. For questions and additional information, please contact Johnson at (765) 494-4800 johnsonk@purdue.edu.
Writer: Julie Douglas, (765) 496-1050, douglajk@purdue.edu.
Source: Keith Johnson, (765) 494-4800, johnsonk@purdue.edu.
Ag Communications: (765) 494-2722;
Beth Forbes, forbes@purdue.edu
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