Protect livestock from prussic acid poisoning

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This time of year we usually get quite a few questions about prussic acid poisoning in livestock. Although prussic acid poisoning can occur anytime during the growing season, the greatest risk is usually associated with the first frost in Kentucky. All ruminants including cattle, sheep and goats can be susceptible to poisoning.
The primary cause of hydrocyanic (prussic) acid poisoning in domestic animals is the ingestion of plants containing this potent toxin. Plants of the sorghum group, including Johnsongrass and leaves of wild cherry trees have a potential for producing toxic levels of prussic acid. There are wide differences among varieties.
The risk from potentially dangerous forages may be reduced by following good management practices:
1. Graze sorghum or sorghum cross plants only when they are at least 15 inches tall.
2. Do not graze plants during and shortly after drought periods when growth is severely reduced.
3. Do not graze wilted plants or plants with young tillers.
4. Do not graze for two weeks after a non-killing frost.
5. Do not graze after a killing frost until plant material is dry (the toxin is usually dissipated within 48 hours).
6. Do not graze at night when frost is likely.
7. Delay feeding silage six to eight weeks following ensiling.
8. Do not allow access to wild cherry leaves whether they are wilted or not.  After storms always check pastures for fallen limbs.
Sorghum grasses are high yielding producers of nutritious forages for grazing livestock but care must be taken to make certain they are grazed properly at this time of the year.
Another potential problem cattle producers may face this season is when grazing corn fields after harvest. Corn yields are very high this year and there may be significant amounts of corn that was not completely harvested, for example corn blown down by wind and missed by the combine. Grazing this is a good idea, but allowing unlimited access to large areas may result in cattle eating just the ears and suffering from lactic acidosis, commonly called foundering. Severe cases of overeating may result in death of the animal. In some cases with cows she may look OK but her calf will be aborted. It only takes about 20 pounds of corn to start causing problems.
The best way to avoid this potential overeating problem is to use temporary electric fence to limit cattle to small areas of a field. According to Dr. Jeff Lehmkuhler, extension beef specialist at UK, cattle in a field yielding 220 bushels to the acre should be limited to about 20 corn plants per head per day.  This will assure they will eat a good mix of grain and forage material; i.e., leaves and stalks. Fence will have to be moved daily because if you fence off enough for three to four days they are likely to eat all four days of ears on the first day and not eat any of the forage material. Feeding mineral with Rumensin will help if they are given access to too much corn, but you have to make sure they are actually eating it.
This is a real problem this year as we have already had producers lose cattle to overeating grain in the field. If you have unharvested grain and would like help in determining the best way to allow your cattle to “harvest” it for you, please call the office.
Although farmers have just begun harvesting this year’s corn and soybeans, it is time to start thinking about planting wheat as well as what crops to grow next year. Wheat is typically planted in Kentucky from Oct. 10-30. After this period yields tend to fall as plants do not have an opportunity to get established before significant freezing and thawing occur. Wheat growers can compensate for this somewhat by increasing seeding rates on late planted fields. Also this year, the wet weather has caused a reduction in residual nitrogen in the field so farmers may want to add an additional 20 to 40 pounds of nitrogen per acre, particularly on fields planted after Nov. 1, or fields following a corn crop.
Farmers also need to consider what they will plant next year. Dr. Greg Halich at UK has developed a model to evaluate planting scenarios based on expected yields, input costs and projected prices. In some areas he projects double crop wheat/soybeans to be the most profitable and in some areas full season soybeans. Corn prices have fallen more rapidly than soybeans so corn does not look as profitable, particularly when considering the yield loss on continuous corn. For more information contact the extension office.
The Marion County Cattlemen’s Association will hold its monthly meeting tomorrow, Thursday, Oct. 10, at 7 p.m. Burkman Feeds is sponsoring the meeting. Call the extension office if you plan to attend.
This Saturday, Oct. 12, the Kentucky Goat Produces and Kentucky Sheep and Wool Producers Associations will hold their annual sheep and goat producer’s conference at the Cave City Convention Center. For more information, call the office or go to kysheepandgoat.org
The Marion County Farm Bureau’s annual meeting will be held next Monday, Oct. 14, at 6 p.m. Contact the Farm Bureau Office for details.
The next “Master Marketer” class for cattle producers who enrolled will be next Tuesday, Oct. 15 at 6 p.m., at the Nelson County Extension Office in Bardstown.
The second session of the Kentucky Beef Network’s weed identification and control series entitled “Treating Your Weeds” will be held Saturday, Oct. 26, from 10 a.m. to 2 p.m. at the Eden Shale Farm in Owen County. Topics will include sprayer technology, what type of herbicides to use for various weeds and when to use them. There is no charge for attending the session. Call the extension office for more information.
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