The process of converting ergot-contaminated grain into feed pellets may decrease its toxicity, contrary to popular belief, according to a recent Alberta Agriculture study.
However, the concentration as well as the types of ergot alkaloids present affects its toxicity to livestock, raising more questions about this harmful fungus.
“The impact of the ergot is going to depend on the form that it came in, so if it’s a pelleted diet, probably having 300 parts per billion is maybe less of an issue than if they’re just feeding rolled grain to their stock,” said Kim Stanford, beef research scientist with Alberta Agriculture and Forestry.
“If the concentration of (ergot) alkaloids gets very high, pelleting alone is not going to be enough to protect the livestock, so I think that’s probably the best information that we’ve got: that pelleting is some help at lower concentrations.”
Stanford, who works out of the Research Centre in Lethbridge, recently completed a three-year study on ergot alkaloids in collaboration with the University of Saskatchewan and Agriculture and Agri-Food Canada. The prevalence of ergot contamination has significantly increased in Western Canada over the last several years, likely due in part to wet conditions. The fungus contaminates grain at the flowering stage, replacing the kernel with an ergot body. “If it’s very wet, humid, cloudy weather when the grain is flowering, that promotes the spread of the fungus,” said Stanford.
“A lot of people are feeding screenings pellets, and when the grain is cleaned that tends to concentrate the ergot, and the livestock bear the brunt of that,” she said. Testing feed for ergot can be extremely challenging. “The ergot alkaloids are very complicated structures, and they’re not easy to measure, so you need very complicated, expensive equipment and really skilled people to do the analyses, and even then it’s difficult.”
One reason that ergot alkaloids are harder to measure than other mycotoxins is because they have two forms, called epimers. The form is based on the rotation of the molecule, and one form of epimer can convert to the other. “It’s kind of a nightmare because we don’t really understand what makes the epimers interconvert back and forth.”
Of the two epimers, the R-epimer is more toxic than the S-epimer. When the R-epimer combines with the receptors in an animal’s cells, it can cause some of the larger problems related to ergot. “The S-epimer doesn’t bind as well, but if it’s going back and forth between those two, it makes it difficult to tell how toxic it is.”
Lambs may be able to withstand higher concentrations of ergot contamination
This study used three different sources of ergot to create the diets that were then fed to lambs. In order to prevent serious issues, researchers were extremely cautious in the amount of ergot-contaminated grain fed in the first year of the study, using 432 parts per billion as the highest concentration. At this step, the study compared pelleted and mash diets with similar concentrations of ergot alkaloids.
“There was a thought within the feed industry that pelleting increased the toxicity of the ergot, but that’s not what we found at all. We actually found that pelleting reduced the toxicity,” said Stanford. Lambs fed the pelleted diet performed better than those fed the mash diet. This was supported by measurements of prolactin in the lambs’ bloodstream. This hormone is used to identify ergot poisoning, as ergot contamination can almost completely stop prolactin production.
While they were able to measure some of the changes in toxicity that took place in the alkaloids, Stanford noted that pelleting didn’t change the actual concentration of the alkaloids. As well, they were not able to measure the epimers present in alkaloids in the first year of the study.
In the second year, researchers increased the concentration of ergot alkaloids to the allowable maximum, 2,400 parts per billion. They used four pelleted diets: a control diet without ergot alkaloids, pellets with a concentration of about 432 parts per billion, about 900 parts per billion and 2,400 parts per billion.
“It took a significantly higher concentration of alkaloids in year two to have an impact on performance, and that was because of the specific types of alkaloids that were present in that sample of screenings that we were feeding to the lambs,” she said.
Stanford explained that this illustrates how problematic ergot contamination is. “There’s wide variations in alkaloids present in ergot.” If a producer tested his feed and found that the concentration was within the allowable limit, this may not mean the feed is safe, as the toxicity also depends on the type of alkaloids present.
In the final year of the study, they added an alkaloid binder to the pelleted diets with the highest concentration of ergot in hopes of preventing negative effects on the lambs. “The lambs that were receiving the binder had 1.7 times more prolactin in their bloodstream compared to the ones that just had the ergot diet,” said Stanford. This is positive, as ergot has serious implications for reproductive functions, though the binder wasn’t able to bring prolactin levels up to those of the control group lambs.
While the lambs fed the ergot-contaminated diet had reduced fibre digestion, the binder recovered fibre digestion in those lambs back to the control group levels. However, it didn’t improve their average daily gain. The binder is also meant to “prevent absorption of the alkaloid in the gastro-intestinal tract,” she said. “The lambs that were fed the ergot-contaminated diet plus binder had 30 per cent more alkaloids in their feces compared to the lambs that were fed the diet with ergot (and) no binder.”
The lambs’ rectal temperatures were taken each week, as ergot leads to vasoconstriction, preventing an animal from properly regulating their temperature. “The lambs that were just receiving ergot without the binder, their rectal temperatures were significantly higher,” said Stanford. While the binder didn’t bring the lambs’ performance up to control levels, it showed that it could potentially “reduce the impacts of heat stress due to ergot exposure.”
Raising more questions
Given the complex nature of ergot, Stanford said that much more work is required. The next step is to investigate how the process of pelleting decreases the toxicity of the ergot alkaloids.
As of April, Stanford and her research group have applied for funding to continue this work. If successful, the next study will be conducted on cattle. “Even though sheep and cattle presently have the same allowable limits based on the current CFIA regulations, which are under review as well, whether sheep and cattle actually do have the same tolerances is another question.”
They also want to investigate the specific types of ergot alkaloids found in the Prairie provinces. “The ergot alkaloids are very location specific, so it’s important that we have some information on what’s here in Western Canada,” she said. Knowing the more prevalent alkaloid profiles in the Prairies would be useful to identify “a bad mixture of alkaloids versus one that may cause less problems.”
Sharing this information with producers is a vital step. “There’s a lot of misinformation about ergot out in the industry,” she said. “There’s a lot of people thinking that if you have 100 parts per billion in your diet your livestock are doomed, and that is not always going to be the case.”