Ergot: Low Levels Cause Big Problems
This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the July 2014 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.
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Ergot develops when a fungus called Claviceps purpurea infects susceptible grass and grain plants during flowering. Rye is most susceptible annual crop, followed by triticale, then wheat. Barley and oats are less susceptible but not completely resistant. Ergot is not a concern in corn. Ergot can also infect a number of perennial grasses. Cool, damp weather conditions during the flowering period (like those in Western Canada over the last few years, and that appear to be shaping up again this summer) cause the flowers stay open longer. This allows more opportunities for ergot spores to spread and infect the seed head. Ergot spores can survive for a year on the soil surface. Less summer fallow, continuous grain-on-grain rotations and un-mowed grass in road allowances allow ergot spores to build up in the soil and help the disease cycle to continue and build.
In infected crops, some of the grain in the seed head will be replaced by black ergot bodies that resemble mouse droppings. These ergot bodies contain toxins called ergot alkaloids. Like all toxins, the severity of their effects depends on how much toxin was consumed, for how long, and the physiological state of the animal. At very high levels (2000 parts per billion, or ppb) in feed, ergot alkaloids will cause dry gangrene of the ears, tails and feet. But more subtle effects (e.g. reduced appetite, growth and performance, prolactin, milk production, reproduction and immunity) start to appear at much lower levels (200 ppb).
Canadian beef nutritionists will soon be able to make more refined feeding and management recommendations regarding ergot contaminated feed. Researchers at the University of Saskatchewan research are using the Prairie Diagnostic Center’s extremely sensitive Liquid Chromatography – Mass Spectrometry (LC-MS) equipment to detect ergot levels as low as 1-3 ppb.
A common recommendation is that grain samples with more than 0.1 to 0.3% ergot bodies by weight will pose a risk to cattle. This roughly equates to 5 to 20 ergot bodies per liter of grain, though this will obviously be affected by the bushel weight of the grain. The Saskatchewan Agriculture Development Fund (SADF) is funding a project led by Dr. Barry Blakley (Toxicology Center), John McKinnon (Animal and Poultry Science), and Jaswant Singh (Western College of Veterinary Medicine). In this study, a grad student is counting the number of ergot bodies per liter in many infected wheat and barley samples varying in bushel weight. Actual ergot alkaloid concentrations will also be determined using the LC-MS equipment. This will lead to better on-farm guidelines for producers to determine when lab testing is recommended for ergot-infected grain samples.
The cow-calf sector doesn’t generally feed a lot of grain, but ergot is also found in the seed heads of annual crops used for greenfeed, swath grazing, or bale grazing. Ergot toxins can be much more highly concentrated in distillers’ grains, screenings, and screening pellets. To better understand the effects of ergot alkaloid levels on cow-calf production, SADF is funding another research project with Drs. McKinnon, Blakley and Singh. In this study, the researchers have formulated pellets containing 39,000 ppb ergot alkaloids by blending barley, canola meal, oat hulls and ergot-contaminated wheat screenings. The pellets have been mixed with silage to create four diets containing 0, 125, 250, or 2000 ppb ergot alkaloids. These diets will be fed to cow-calf pairs for one week. Blood samples will be collected and analyzed for the hormone prolactin. Ultrasound will be used to measure blood flow in the uterus and tail. This project will help identify the ergot alkaloid levels that first start to subtly affect the cow’s physiology. Based on these results, the diets will be refined and a follow-up experiment will collect longer term measurements on cow reproduction and pre-weaning calf growth.
We also don’t know when ergot bodies start to develop in the seed head, when ergot alkaloids first appear, or how fast they accumulate in the ergot bodies. The Saskatchewan Ministry of Agriculture, led by regional livestock specialist Sean Thompson, will collect seed heads throughout the summer from a variety of ergot-infected grain crops around the province. These samples will be analyzed for ergot levels using the LC-MS equipment to determine how ergot alkaloid levels change as the crop develops. This will help determine how early ergot alkaloids can be detected in the seed, how fast ergot alkaloids accumulate in the seed, and help to develop better recommendations around the use of ergot-infected crops for swath-grazing, bale-grazing, greenfeed or silage.
For more information about ergot, and how to identify, sample, test for, and deal with it in feed grain and screenings:
- Ergot Spotted in Western Canada: Keep an Eye Out (BCRC Blog post)
- Ergot: Low Levels Cause Big Problems (Canadian Cattleman Magazine)
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