Johnson Grass Toxicity

[nap]

Johnson grass is about the only thing growing in our pastures during this extended drought. Knowing there is a toxicity issue we decided to have it tested by the state lab here in Arkansas. For testing we collected 8 samples randomly. To our dismay, each sample tested over 100 ppm prussic acid which is a highly toxic level. In fact, after the results were reported the state pathologist called us to get more information. She informed us that these were the highest levels they had tested in quite some time. Fortunately, I have Johnson grass free areas that I can use for very limited grazing. Which means, of course, that I am forced to feed more hay and supplement. Have any of you had experience with this? How long will the grass retain its toxicity? Have any of you actually lost animals? I am anxious to hear your opinions and stories.
nap

 

[1982vett]

Rule of thumb....(as far as rules go)...two weeks after the stressed grass has recovered....so you just have to figure out when to start counting your two weeks. Now the question for me that always remains...easy to know when the first stress relief occurs...but usually a week after the relief comes it is stressing again (that 30 day or more interval between beneficial rain). Is it toxic again...

I suppose the best thing to do since you know you have a problem is to check it again in two weeks. If you were able to cut for hay, the time for it to dissipate during curing is at least 5 days.

 

[calfbuyer]

I have always been told that if they are grazing it when the grass begins to stress and gets the prusic acid build up, it wont bother them.But if you turn in on a patch that has the prusic acid problem, then you will have big problems.
I have a bunch of light weight calves turned out on johnson grass that is stressed and turning brown right now. I turned them in on it when it was lush and green about a month ago though.

 

[1982vett]

I have always been told that if they are grazing it when the grass begins to stress and gets the prusic acid build up, it wont bother them.But if you turn in on a patch that has the prusic acid problem, then you will have big problems.
I have a bunch of light weight calves turned out on johnson grass that is stressed and turning brown right now. I turned them in on it when it was lush and green about a month ago though.

Maybe more like the prussic acid formation is after relief from stress in which constant grazing prevents a buildup of enough concentration to be a problem....My understanding of all I've read about it.

I did turn in on some Johnson Grass infested pasture Tuesday following this protocal (two weeks after moisture stress recovery). So far nothing dead...which should have happened Tuesday if it were present.

 

[Goodlife]

I recently purchased a field that had winter wheat in the spring. Sitting idle right now to convert it to pasture. Like you said, with the drought Johnson Grass is the primary grass growing right now (along with lots of Queen Annes Lace also called Wild Carrot Weed). A couple of questions:

While it is noxious in some stages, do cattle like Johnson Grass? Is it nutritious?

Being in the early stage and about a year or so till I plan to introduce cattle to the pasture, do you have any recommended steps I should take right now? I am planning on having it disced in a month or so to chop up the wheat stalks. Will the fescue native in this area recover and eventually overtake the johnson grass if I simply disc and mow next year? I do not have a soil sample but will get one soon.

Thanks
Ed

 

[nap]

I'm not sure of its nutrition value, perhaps someone else can comment. My cattle love it, it is the first thing to go for when I turn them in.

 

[calfbuyer]

Cattle love johnson grass, especially when its young and tender. after it heads out, its like anything else it gets tough and rank.

If it has already headed out then you will have it next year. Seems like the more you disc it and try to get rid of it, the more of it you have.

If you put cattle on the pasture and leave them in there then the johnson grass will go away in 2 or 3 years because the will keep it eaten down and it will never get a chance to head out.

 

[CowboyBlue]

My grandfather's generation swore by Johnson grass as far as grazing and baling for hay, as long as it wasn't in the toxic stage. My father would often let in one or two cows at a time in a fenced pasture or field of Johnson grass, to see if it was poison. He said it wouldn't take long to find out; a cow woud be on her side and kicking in about fifteen minutes ... Thankfully, I never saw that happen.

 

[nap]

Seems like kind of an expensive way to test. Fortunately, here in Arkansas they will do a lab test for 10 bucks a sample.

 

[Goodlife]

I did a little looking and nuitrition wise Johnson Grass seems almost identical to Fescue with 10-14% crude protein and 50-60% total digestible nutrients. So other than during a drought, this seems like good pasture grass. The prussic acid issue seems very scarry though. Since a drought is what raises the prussic acid levels, has anyone on these boards lost any cattle this year due to toxic JG?

 

[salebarn junkie]

Your county extensionee office should be able to answer your questions. I would brush hog it let set for a week then but the cattle on it. The way i understand it when it under a foot its safe and when its mature and over 22 inches its safe. Its most dangerus after a rain and after first frost. I wouldent take chance on it with advice from a board but would talk to profesional

 

[nap]

Times like this make me wonder what I'm doing in the cattle business. Two years of extreme drought and now toxic grass. I expect to see a cloud of locusts on the horizon any minute now. On the other hand, I don't know why locusts would come here. They would starve to death.

 

[whitecow]

If the locusts came here, they could feast on the grasshoppers. They seem to be the only thing growing around here this summer. I have no idea what the grasshoppers are living on.

 

[tsmaxx47]

what are the symtoms of prussic acid toxicity?

 

[nap]

As I understand it the prussic acid is converted to HCN in the animal. The symptoms are similar to those of cyanide poisoning. The animal staggers, the mucous membranes turn cherry red, there is gasping for air followed by collapse. It is over in a matter of minutes. This is something to be taken very seriously. Is there anyone out there that has lost cattle do to Johnson grass toxicity?

 

[Fire Sweep Ranch]

We have had several losses reported out here in SW Missouri, unfortunately. None of ours, but we do not graze it when we see it. Too scary to lose cattle because we do not know for sure if it is toxic or not. We have been feeding hay since the end of June, and I am trying to save the pastures for when we get a good fall rain (hopefully) and the pastures will bounce back quicker than if I grazed them short. Might be wishful thinking, but I hope not! The patches if Johnson grass are about 5 foot tall and look good! To me and my cattle

 

[1982vett]

what are the symtoms of prussic acid toxicity?

The symptoms are dead animals. They basically graze a bit and fall over dead. Not much time to observe symptoms. But you can save the ones still standing if your fast enough with the antidote....sodium nitrate or sodium thiosulfate

http://aces.nmsu.edu/pubs/_b/B-808.pdf

 

[tsmaxx47]

what are the symtoms of prussic acid toxicity?

The symptoms are dead animals. They basically graze a bit and fall over dead. Not much time to observe symptoms. But you can save the ones still standing if your fast enough with the antidote....sodium nitrate or sodium thiosulfate

http://aces.nmsu.edu/pubs/_b/B-808.pdf

very informative - thanks vette.........

 

[nap]

We just had another three samples of Johnson grass tested at the state lab. This is a full two weeks after the first test in which eight out of eight samples had toxic levels of prussic acid. The latest test results show all three samples were over 100 ppm hydrogen cyanide which is highly toxic. We have not had any rain for over two weeks so the toxins have been for over after two weeks after the last rain. Proceed with caution!

 

[Goodlife]

JG sure seems too dangerous to mess with. If you don't mind me asking, do you use the extension service for this testing and how much do they charge? You make it seem so easy to get it tested.