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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. [ABSTRACT FROM AUTHOR]

The effects of pelleting feed containing cereal ergot alkaloids was evaluated in performance and nutrient digestibility trials using growing lambs. Defined concentrations of ergot alkaloids [Control (C), no added alkaloids but background concentrations of ∼3 ppb; Low (L), ∼169 ppb; High (H), ∼433 ppb] were achieved by substituting barley grain for ergot-contaminated screenings containing (fed basis) approximately 538 g/kg barley grain, 300 g/kg alfalfa and 160 g/kg canola meal. Diets were fed either as a mash or as a completely pelleted feed. Total alkaloid concentrations did not differ between corresponding mash and pelleted diets, but ergotamine and ergosine were 2–3 times greater in mash feeds, while ergocornine, ergocristine and ergometrine were 2–3 times greater in pelleted diets. The total collection digestibility experiment used 12 ram lambs in a crossover design with 3 experimental periods. Alkaloid dose did not affect digestibility of DM, OM, or CP, but NDF and ADF digestibilities were linearly reduced ( P < 0.05) with increasing alkaloid dose. Alkaloid concentrations in feces depended upon the specific type of alkaloid measured. In preliminary results, ergocristine and ergotamine were the only alkaloids in higher concentrations ( P < 0.001) in feces from lambs fed H as compared to C diets. In the growth experiment, ram and ewe lambs (live weight 24.6 ± 1.08 kg) were randomly assigned to diets, weighed weekly and fed to a slaughter weight of ≥45 kg. Dietary treatments did not affect carcass characteristics, although serum prolactin concentration was linearly reduced ( P < 0.001) by increasing alkaloid dosage and was lower ( P = 0.01) in lambs fed mash as compared to pelleted diets. Although pelleted diets had total alkaloid concentrations that were similar to mash diets, lambs fed pelleted diets had 60 g/d greater ( P < 0.001) ADG than those fed mash diets. For H diets, lambs had lower ADG and feed conversion ( P = 0.03) than those fed C or L, Based on the results of this study, pelleting diets reduced negative impacts of ergot alkaloids possibly by changing alkaloid profiles. [ABSTRACT FROM AUTHOR]