Frosted Summer Annuals- NOW WHAT?

October 22, 2019

David Hunsberger – King’s AgriSeeds, Central Regional Coordinator

As the calendar marches its way into late October nighttime temperatures drop and we will be seeing Frost nip our plants into submission. While we acknowledge dates are dependent on latitude, elevation, and cloud cover to name just a few we all know the event will happen as autumn wanes and winter sets in.

Forage Sorghums, Sorghumxsudans, johnsongrass, grain sorghums, and sudangrass all will release hydrocyanic or Prussic acid as the cell walls are ruptured in the freezing process. Millets do not have this precaution. The consumption of prussic acid will inhibit the blood’s ability to carry oxygen and the animals will suffer asphyxiation and most likely die if they consume even a small amount, only 2mg/pound of BW per hour. The poison is very fast acting, 2 compounds are effective in treatment, sodium nitrate and sodium thiosulfate. These need to be administered IV, consult your herd veterinary practitioner for instructions on actual treatment.

Frost occurred, Now What? If you are actively grazing a sward of susceptible forages you must stop and pull the livestock off the affected paddocks immediately following the frost event. It will be safe to return to grazing in 7-10 days when the leaves of the affected plants are dry. They will appear brown in color like a paper lunch sack. If you have successive frosts or if you go 5-6 days and then get a frost hit again you must begin to count your days to safety all over again. If you have a significant amount of forage left that you wish to make use of you can safely cut and process it into silage. Either baling and wrapping or cutting and filling a silo, agbag or pile. The key to this is to ensile it, mark your calendar 30 days and wait until then to open up the storage and feed. The fermentation process and the 30 day interval will allow the cyanide gas to dissipate out of the forage and you can safely feed it. A word of CAUTION:

So often when we are making fermented feed there is a ½ round bale left over or there is a pile at the blower or around the horizontal silo structure that needs to be cleaned up post harvest. General practice is to scoop it up and feed to some heifers or a tmr batch not going to fresh or high group cows. RESIST this action either get it into the structure or “under wraps” or put it into the manure spreader or compost heap!! This little slip has cost some producers.

Sorghums can be fed without incident if you keep these practices in mind and follow through, we wish you success as the growing season passes and we look forward to serving you in 2020!