If you’ve been wary when fall-grazing alfalfa because of the risk of nitrate poisoning, you’ve been right to be careful, but for all the wrong reasons. Because alfalfa is a perennial legume, nitrogen is fixed and stored in the nodules of its root system and doesn’t actually accumulate in the tissues (something that can be concerning in annual crops — hence the push to swath before frost).
A genuine concern for fall grazing of alfalfa, however, is the increased risk of bloat. A killing frost results in ruptured cell walls in the plant, meaning gas is more readily released and bloat is more likely. If you intend to graze following temperatures of -5 degrees C or lower, it’s actually best to wait for plant dry-down to occur before turning animals out.
In this video, Sarah Sommerfeld, regional forage specialist with the Saskatchewan Ministry of Agriculture, provides some tactics for producers to mitigate the risk of bloat when fall grazing alfalfa stands.
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