The negative impacts of ergot contamination of grain on the health of humans and animals were first documented during the fifth century AD. Although ergotism is now rare in humans, cleaning contaminated grain concentrates ergot bodies in screenings which are used as livestock feed. Ergot is found worldwide, with even low concentrations of alkaloids in the diet (<100 ppb total), reducing the growth efficiency of livestock. Extended periods of increased moisture and cold during flowering promote the development of ergot in cereal crops. Furthermore, the unpredictability of climate change may have detrimental impacts to important cereal crops, such as wheat, barley, and rye, favoring ergot production. Allowable limits for ergot in livestock feed are confusing as they may be determined by proportions of ergot bodies or by total levels of alkaloids, measurements that may differ widely in their estimation of toxicity. The proportion of individual alkaloids, including ergotamine, ergocristine, ergosine, ergocornine, and ergocryptine is extremely variable within ergot bodies and the relative toxicity of these alkaloids has yet to be determined. This raises concerns that current recommendations on safe levels of ergot in feeds may be unreliable. Furthermore, the total ergot alkaloid content is greatly dependent on the geographic region, harvest year, cereal species, variety, and genotype. Considerable animal-to-animal variation in the ability of the liver to detoxify ergot alkaloids also exists and the impacts of factors, such as pelleting of feeds or use of binders to reduce bioavailability of alkaloids require study. Accordingly, unknowns greatly outnumber the knowns for cereal ergot and further study to help better define allowable limits for livestock would be welcome.

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Allowable limits for cereal ergot alkaloids in livestock feeds are being re-examined, and the objective of this study was to compare nutrient digestibility, growth performance and carcass characteristics of ram lambs fed a range of alkaloid concentrations, including the maximum currently allowed in Canada (2 to 3 ppm). Four pelleted diets were fed: control, with no added alkaloids; 930; 1402; and 2447 ppb alkaloids based on total R and S epimers. Eight ram lambs (30.0 ± 3.1 kg) were used to examine the impacts of dietary treatments on nutrient digestibility and alkaloid recovery from feces. Concentrations of dietary alkaloids evaluated did not affect nutrient digestibility or N metabolism. Excepting ergocornine and ergocryptine, recovery of alkaloids in feces varied among periods, suggesting that individual lambs may differ in their ability to metabolize ergocristine, ergometrine, ergosine, ergotamine and their S epimers. In a second experiment, ram lambs (n = 47, 30 ± 8 kg) were randomly assigned to a diet and weighed weekly until they achieved a slaughter weight of ≥ 45 kg (average 9 weeks; range 6 to 13 weeks). Intake of DM did not differ (p = 0.91) among diets, although lambs fed 2447 ppb alkaloids had a lower (p < 0.01) ADG than did lambs receiving other treatments. The concentration of serum prolactin linearly declined (p < 0.01) with increasing alkaloids. Feeding 2447 ppb total alkaloids negatively impacted growth, while feeding 1402 ppb did not harm growth performance, but reduced carcass dressing percentage. Due to different concentrations of alkaloids affecting growth and carcass characteristics in the present study, determining allowable limits for total dietary alkaloids will require a better understanding of impacts of alkaloid profiles and interactions among individual alkaloids.