When some forages are frosted, the potential for bloat, toxicity, and nitrates could improve for grazing cattle.
Bloat
When grazing alfalfa within the fall, bloat stays a possible downside, particularly through the first three to 5 days after alfalfa has been uncovered to freezing temperatures. Usually, the chance of bloat shall be minimal solely after a good portion (about 50-70 p.c) of the alfalfa high progress has been frozen and dried. The autumn freeze-down is usually a gradual course of with many freezes over a number of weeks. The time it takes to succeed in the purpose the place 50 to 70 p.c of the alfalfa high progress has been frozen and dried will rely upon the severity of the freezes and quantity of standing alfalfa.
Prussic Acid
When grazing sorghums (forage or grain), sorghum-sudangrass hybrids, and sudangrass, sure situations could trigger livestock to be poisoned by prussic acid (hydrocyanic acid or cyanide). Frost is one in every of these situations. Crops which can be frozen could launch excessive concentrations of prussic acid for a number of days. After the plant wilts, prussic acid launch from the plant tissues will decline. Thus, you need to take away cattle earlier than a frost after which wait a number of days (5-7) after a frost to show livestock onto these species to graze. When tops have been frosted, new shoots could regrow on the base of the vegetation. These may be excessive in prussic acid. Thus, don’t graze frosted sorghum or sudan species regrowth till regrowth is 15-18 inches tall for sudan species and 24 inches tall for sorghum species. Another choice is to attend a number of days after your complete plant and shoots are killed by subsequent frosts. Sorghum species include the best quantity of prussic acid whereas sudangrass usually has the least quantity. Sorghum-sudangrass hybrids are normally intermediate. Prussic acid manufacturing potential could improve with excessive nitrogen charges.
Pearl millet and foxtail millet haven’t brought on prussic acid poisoning and prussic acid has not been present in these vegetation.
Nitrates
Frost interferes with regular plant progress and might trigger nitrates to build up in vegetation which can be nonetheless rising, particularly grasses like oats, millet, sorghums, and sudangrass. If excessive nitrates are current within the vegetation once they bear a complete killing freeze, that nitrate stage will stay in these vegetation and testing the forage is advisable.
For additional info on the results of frost on forages, please go to beef.unl.edu and the references under.
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