Fall-grazed alfalfa can be a low-cost feed for cattle producers, but steps must be taken to prevent losses from bloat, say South Dakota State University (SDSU) forage experts.

If you move cattle to fields that haven’t yet frozen, pay close attention to the weather, they advise. During a frost or freeze, the cell walls rupture, releasing more soluble protein inside plants and increasing the risk of bloat in cattle.

If a frost or freeze occurs when cattle are grazing alfalfa, they should be pulled immediately and kept off the field for at least three days. If it wasn’t a killing freeze and just a frost, each subsequent frost or freeze needs to be monitored for additional plant damage.

The SDSU experts list these additional management recommendations:

  • Wait until alfalfa is in full bloom to graze to reduce bloat incidence.
  • Feed a bloat-preventing compound, such as poloxalene, for several days before and after the start of grazing alfalfa.
  • Fill cattle up with good-quality grass hay before moving them to alfalfa fields.
  • Move cattle into alfalfa in late morning or the afternoon, not in early morning.
  • Monitor cattle for bloat incidences several times per day for the first three days of grazing, then once a day, preferably mid-morning.
  • Have an escape pasture in case cattle have to be moved promptly.

In addition to feed savings during fall and winter months, grazing after frost helps control alfalfa weevils, say the experts. Weevil eggs in stems are consumed, reducing the number available for hatching the following spring. However, take caution if weather conditions change from dry to wet, as grazing alfalfa in wet, muddy conditions can damage crowns.