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Department of Agronomy > Agronomy Extension

It's Autumn

The Question

I have had some questions about the frost or freeze we had last night and how this will effect cows. The farmer took them out of the field.  How long will he need to wait to put them back in the field? Does this have a real effect on cattle if alfalfa has had frost?  Thanks.

My Answers

They might seek a warmer spot to spend the night.

As you can tell by the above response, there is no prussic acid issue associated with alfalfa as has been documented with members of the sorghum family.  One commonly used forage, white clover, has been shown to have the potential for toxicity from the formation of prussic acid.  I never have been informed of a documented case of prussic acid poisoning from white clover in my career.

Bloat-prone livestock that are allowed to graze potential bloat-causing legumes, can be more at risk when there is moisture on the legumes (dew,rain, frost), plants are more lush, and legumes are predominant as compared to grasses.  Bloat-reduction strategies should be considered.

Back to Forage Issues

Keith Johnson
Professor of Agronomy and Forage Crops Specialist
1150 Lilly Hall of Life Sciences
West Lafayette, IN 47907-1150
phone: 765-494-4800
fax: 765-496-2926



For more forage information contact Dr. Keith Johnson: johnsonk@purdue.edu

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