Until August we had a great summer, but now we are slipping into dry conditions here in Comanche County.
With these conditions comes many problems, one of those is the risk of prussic acid in stressed forages.
With all the good early rainfall you may have an abundant supply of Johnson grass in some of your fields.
Also, many folks planted sorghum-sudangrass hybrids and forage sorghum and probably got a good hay cutting.
Many of those fields grew back to some extent and it may be tempting to want to turn the cows out on them now that grass is getting short.
However, with the now dry stressful conditions, both scenarios have the potential to create prussic acid poisoning issues.
It is best to be extra careful when grazing forage with the potential to build up high levels of prussic acid. If prussic acid is a concern, you should consider testing forages for high levels of prussic acid.
Prussic acid poisoning is a threat to grazing livestock that are grazing forages that may accumulate prussic acid.
The threat of prussic acid accumulation is much greater when these forages are stressed from drought, frost, herbicide injury or other types of stress.
Forages that have the potential to accumulate prussic acid at high levels include: Johnsongrass, grain sorghum, forage sorghum, and sorghumsudangrass hybrids. Sudan and sudan grass hybrids have a low to moderate chance of accumulating prussic acid.
Prussic acid in livestock occurs when they graze forage with high levels of prussic acid otherwise known as cyanogenic glucosides.
These glucosides are actually sugar compounds that are broken down in the rumen; this frees the hydrocyanic acid (HCN) otherwise known as cyanide from the sugar.
Cyanide poisoning in l ivestock causes respiratory stress and is very fast acting; death will occur quickly.
Treatment is possible with sodium nitrate and sodium thiosulfate and treatment can be effective, but must occur quickly after the initial symptoms to be successful.
Perhaps the best way to guard against prussic acid poisoning is to cut the forage for silage or hay. This will allow the HCN to volatilize. It is best to store the hay for some time to be sure volatilization has occurred.
Cattle are worth a lot right now and risking a loss to prussic acid may not be worth the extra grazing.
But if you are forced to graze fields that have stands of grasses that are susceptible to storing moderate to high levels of prussic acid, you may want to consider testing before turning cattle out.
Unfortunately, since prussic acid is volatile and the levels in the plants can change quickly, even with a good test, extra steps should be taken to prevent losses.
I recommend that you never turn hungry cattle onto fields at risk, even those that have been tested. Make sure the cattle are full of hay or other forages before turning them out, this will prevent the cattle from overloading on the at risk forage and lessen the risk of prussic acid poisoning.
Probably also a good idea to gate cut a couple of head and let them graze a few hours before turning in the whole herd. If they appear to be fine, then you should be good to turn the whole bunch out.
As always, watch your cattle closely for a day or two after turning them out on at risk fields.