Fescue Toxins

ELDON COLE

MT. VERNON, MO.
   Earlier this month I had a call from a farmer who had a field of season-long fescue growth. He asked if I thought it would be risky to turn third stage dairy heifers in on it for fear of fescue foot. I told him we might sample it to see what the ergot alkaloid level was but it would cost close to $100. That didn’t bother him so we went out and collected samples and submitted them to the University of Missouri Veterinary Diagnostic Lab.  Less than a week later, the results came back showing ergovaline levels at 70 parts per billion (ppb). That is not a scary number for fescue problems. Our threshold is considered to be 100 to 200 ppb.
   A week later I received the total ergot alkaloid levels and they were also low or non-detectable. In the past, testing for toxins in fescue was primarily done with the search for the fungus and not the various alkaloids. I like this new approach and maybe the price can be lowered in time.
   The dairyman was already planning to feed the heifers some alfalfa and bermuda hay along with 4 or so pounds of commodity mix as they grazed the rank fescue. This supplementation should easily dilute the toxin level had it been over 200 ppb.
   The very next week a beef cow herd owner contacted Tim Schnakenberg about his herd’s fescue foot and bob tail problem. Tim and I visited the farm and sure enough I estimated 15 or 20 cows out of 100 plus cows showed symptoms of toxicity. Some had only missing tail switches while others were limping big-time on their rear limbs. The affected cows had lost weight, moving into the 4 body condition score range. When preg checked, the preg rate was only 72 percent.
   As bad as the lameness was, something hit me as soon as I saw the cows. Several of them had very prominent briskets. The large briskets were on some of the more fleshy cows and not the limpers.
   I’ve checked with our fescue folks at MU and they’d never seen this phenomenon. I knew I’d never seen a sight like that. What has haunted me for a long time is thinking about the possibility of high mountain disease (HMD) and fescue toxicosis being somehow genetically linked. Both conditions result in compromised blood circulation. The HMD is noted at high elevations in the mountain west and the cattle have probably never seen a sprig of fescue or ergot alkaloids.
   Genetic testing might somehow reveal a relationship but I’ll leave that to the researchers. I visited with Ted Dahlstrom, DVM at Monett and Joplin Stockyards. Ted said he occasionally did see “fescue cows” with large briskets and maybe their poor circulation could result in edema in the brisket. We may observe large briskets with cows suffering from hardware disease. If you’ve noticed this let me know. ∆
   ELDON COLE: Extension Livestock Specialist, University of Missouri
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