THE IMPACT OF PROCESSING ERGOT INFECTED GRAINS ON PRODUCTION PARAMETERS AND NUTRIENT DIGESTIBILITY IN SWINE

Abstract

Ergot alkaloids (EAs), secondary metabolites produced by the fungus, Claviceps purpurea, infect cereal grains and grasses. The exposure of livestock to ergot contaminated feed results in symptoms ranging from reduced feed intake to death. Six EAs are commonly detected in Saskatchewan grains, and each exists as either an ‘R’ or ‘S’ epimer. Toxicity of ergot is affected by EA content, alkaloid and epimer profile, with most research indicating the R form to be more potent than the S form. There is some indication that hydrothermal processing may reduce ergot toxicity, perhaps by changing the epimer profile. The objective of this study was to investigate the effects of hydrothermal processing on the alkaloid content and epimer profile of ergot infected wheat and rye screenings and determine if this is related to toxicity. In trial 1, heavily contaminated screenings were processed with either steam explosion, pelleting, or extrusion. Samples used for trial 1 included screenings and diet samples. Screenings were heavily contaminated rye screenings that were either steam exploded for 2 or 5 mins, or, harsh or mild pelleted, and wheat screenings that were soaked or unsoaked before steam explosion. Diet samples were obtained from previous swine experiments which contained processed (steam exploded or extruded). All samples were analyzed for EA and epimer content by liquid chromatography mass spectrophotometry (LCMS). Total EA content of the screenings were reduced by 96 % in the diet containing steam exploded premix relative to the diet containing the non steam exploded premix. There was, however, no effect of extrusion on total EA content in diets containing the extruded premix. Steam explosion for 2 or 5 mins reduced the content of ergot of screenings from between 39-42 %. Mild pelleting had minimal effect (<15 %) while harsh pelleting reduced the ergot content by 25 % compared to the control. Steam explosion reduced the ergot content in wheat screenings, regardless of pre-soaking. Steam explosion resulted in greater reductions of individual EAs when than extrusion or pelleting. The relative changes were more consistent for all individual EAs with the exception of ergocristine. The change in epimer profile was not consistent comparing steam explosion and extrusion for the diets containing 4000 ppb processed contaminated screenings (premix). Steam explosion reduced both R and S epimers whereas the change observed with extrusion was due to consistent increases in S epimers but a reduction of the R. With the change in epimer profile observed with the extrusion of ergot-contaminated screenings in trial 1, a feeding trial (trial 2) was conducted by incoporating premixes(formulated for the purpose of this study) that were processed by extrusion to investigate whether a change in epimer profile will result in reduced toxicity (negative effects) in growing pigs. In trial 2, diets containing 0 or 4000 ppb EA, extruded or not (2 × 2 factorial) were fed to 160 pigs (5 pigs per pen) from 65 ± 4 kg to 125 kg BW in a 56d performance trial. Blood samples collected on d7 and d56 were analyzed for prolactin, a sensitive indicator of ergot toxicity. A third trial was conducted to determine the effects on nutrient digestibility of pigs fed 1 of these 4 treatment diets with the inclusion of celite. Growth (ADG) and feed intake (ADFI) decreased when pigs consumed EA contaminated diets (1.07, 1.03 kg/d; 0 and 4000 ppb, P<0.05) and (2.97, 2.78 kg/d; 0 and 4000 ppb, P<0.05) respectively. Serum prolactin (ng/mL) was reduced on d7 (1.67, 0.57; P<0.05, 0 and 4000 ppb) and on d56 (0.71, 0.43; P<0.05, 0 and 4000 ppb) when pigs consumed EA contaminated diets. Extrusion had no effect on ADG, ADFI, FE or serum prolactin (P>0.05). There was a tendency for reduction of N ATTD (P=0.06) due to ergot. There were no ergot by extrusion interactions on any of the performance parameters, ATTD of N or serum prolactin (P>0.05). The results indicated that the consumption of diets by growing pigs contaminated with 4000 ppb EA had modest effects on performance and nutrient digestibility of growing pigs. Extrusion changed EA epimer profiles but did not reduce the toxicity (negative effects) of ergot-contaminated screenings. Further research is required to investigate appropriate and practical hydrothermal technologies to reduce EA toxicity.