Tips when feeding unharvested crops

Digestibility, nutrient levels, and presence of mycotoxins are factors to consider before swath grazing or baling

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Using overwintered cereal crops for swath grazing this spring — or baling for use as greenfeed next fall and winter — is an option but raises some concerns.

“Typically, protein and energy contents are lower in the spring compared to the fall,” said provincial beef and forage specialist Barry Yaremcio. “Digestibility of the feeds can be reduced as well. In the case of greenfeed or swath grazing, digestibility could be up to 10 per cent lower.”

That means unthreshed crops or spring-threshed grain need to be blended with other feedstocks to improve quality.

As well, animals in late pregnancy or in lactation have approximately 25 to 30 per cent higher nutrient requirements than animals in early or mid-pregnancy.

“While there are differences between species, this trend is true for all,” said Yaremcio. “As a result, spring swath grazing or cereal greenfeed harvested from overwintered crops need to be tested for quality, and rations need to be balanced to meet animal requirements.”

Mycotoxins are another concern. They are often found in cereal crops but are much less common in canola and legumes as the fungi that can produce mycotoxins “predominantly infect the seed head and not the stems or leaves of the plant.”

“If the weather is reasonably mild with high relative humidity, conditions are ideal for mycotoxin development,” said Yaremcio. “Ergot concentrations appear to reach maximum values by mid- to late July. Levels remain stable for ergot. Levels of some of the fusarium mycotoxins can increase when grain is in storage.”

Testing is critical, he added.

It’s important to test for the presence of mycotoxins, not the type of microbes or populations present on the material,” he said. “If feed test results indicate that there is sufficient nutritional quality to feed to livestock, then testing for mycotoxins is required before any of the material is actually fed to the livestock.”

For more detailed information, go to www.agriculture.alberta.ca and search for ‘overwintered crops.’

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