Dietary Deoxynivalenol Research Articles

The influence of the mycotoxin deoxynivalenol on jejunal glucose transport in pigs

The experiments were aimed at evaluating whether the activity of the glucose transporter in the pig's jejunum is affected by deoxynivalenol (DON)-contaminated feed. This is based on the ability of DON to inhibit the protein synthesis on cellular level which might also involve the synthesis of the intestinal glucose transporter.Two groups of six castrated male pigs were restrictively fed a control or a DON contaminated diet (=5.7 mg/kg). Immediately after slaughtering the pigs, the mid-jejunum was quickly dissected, washed, frozen and stored at -80°C until preparations. Brush border membrane vesicles (BBMV) were prepared by Mg(2+)-EGTA-precipitation and differential centrifugation. The activity of the glucose transporter was examined by measuring the uptake of [(3)H]-glucose into the BBMV. The glucose uptake was quantified by using the rapid filtration technique.The glucose uptake into BBMV followed Michaelis-Menten-kinetic. Comparison of the kinetic parameters Vmax (transport capacity) and Km (transport affinity) of the two treatment-groups showed no significant differences between feeding a DON-contaminated or control diet. It was concluded that dietary DON exposure (=5.7 mg/kg) for five weeks had no obvious influence on the intestinal glucose transporter and its activity in pigs.

Study on the transmission of deoxynivalenol and de-epoxy-deoxynivalenol into eggs of laying hens using a high-performance liquid chromatography-ultraviolet method with clean-up by immunoaffinity columns

The transmission of deoxynivalenol (DON) and of its metabolite de-epoxy-DON into eggs has not been sufficiently elucidated until now. This question was addressed within the scope of a 16-week experiment with laying hens which were fed a maize-based diet with a DON concentration of 11.9 mg x kg(-1 )dry matter. Eggs were collected during weeks 2, 4, 8, and 16 of the experiment, and DON and its metabolite de-epoxy-DON were analyzed in freeze-dried yolk and albumen. In order to cover possible conjugates, all samples were incubated with beta-glucuronidase prior to extraction. Yolk and albumen were extracted with acetonitrile-water, and the extracts were purified with immunoaffinity columns (IACs) after a precleaning step. The toxins were determined by high-performance liquid chromatography (HPLC) with UV detection. The detection limits of both toxins were 5 and 8 microg x kg(-1) in freeze-dried yolk and albumen, respectively, corresponding to approximately 2.5 and 1 microg x kg(-1) in fresh samples. The recovery of DON and de-epoxy-DON in yolk was 80% and 78%, respectively, and in albumen 77 and 72%. Neither DON nor de-epoxy-DON or glucuronide conjugates of both substances could be detected in any of the samples. These results indicate that eggs do not contribute significantly to the dietary DON intake of humans.

Carry-over of deoxynivalenol into eggs of laying hens — Preliminary results

Carry-over of deoxynivalenol (DON) into eggs was investigated within the scope of a 16-week experiment with laying hens, in which the birds were fed a maize-based diet containing DON at 11.9 mg/kg dry matter. Eggs were collected during weeks 2, 4, 8, and 16. DON and its metabolite deepoxy-DON were analysed separately in freeze-dried yolk and albumen. Yolk was extracted with water and the extract was purified using an immunoaffinity column (IAC). Albumen was extracted with acetonitrile-water and the extract was pre-cleaned before applying an IAC. All albumen and some yolk samples were incubated with β-glucuronidase prior to extraction. DON and de-epoxy-DON were determined by high performance liquid chromatography (HPLC) with diode array detection (DAD). The detection limits of both toxins were 20 ng/g and 15 ng/g in freezedried yolk and albumen, respectively, corresponding to approximately 10 ng/g and 2 ng/g in fresh samples. The recovery of DON/de-epoxy-DON in spiked samples (50-200 ng/g) was 87/83% (yolk) and 87/77% (albumen) with coefficients of variation of 4-15%. Neither DON nor de-epoxy-DON were detected in any of the samples. In order to achieve lower detection limits, the methods are currently optimized. However, these preliminary results indicate that eggs do not contribute significantly to the dietary DON intake of the consumer.

Docosahexaenoic Acid and Eicosapentaenoic Acid, but Not α-Linolenic Acid, Suppress Deoxynivalenol-Induced Experimental IgA Nephropathy in Mice

Diets enriched in the (n-3) PUFAs, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and their precursor alpha-linolenic acid (ALA), were evaluated for efficacy in ameliorating the development of IgA nephropathy (IgAN) induced in mice by the mycotoxin deoxynivalenol (DON). The effects of DON were compared in mice that were fed for 18 wk with AIN-93G diets containing 1) 10 g/kg corn oil plus 60 g/kg oleic acid (control); 2) 10 g/kg corn oil plus 35 g/kg oleic acid and 25 g/kg DHA-enriched fish oil (DHA); 3) 10 g/kg corn oil plus 33 g/kg oleic acid and 27 g/kg EPA-enriched fish oil (EPA); and 4) 10 g/kg corn oil plus 37 g/kg oleic acid and 23 g/kg DHA + EPA (1:1) enriched fish oil (DHA + EPA). The DHA, EPA and DHA + EPA diets attenuated induction by dietary DON (10 mg/kg) of serum IgA and IgA immune complexes, kidney mesangial IgA deposition, and ex vivo IgA secretion by spleen cells. Consumption of the DHA + EPA diet for 8 wk significantly abrogated the DON-induced gene expression of interleukin (IL)-6, a requisite cytokine for DON-induced IgA nephropathy, in spleen and Peyer's patches. Finally, incorporation of ALA-containing flaxseed oil up to 60 g/kg in the AIN-93G diet did not affect DON-induced IgA dysregulation in mice. Taken together, both DHA and EPA, but not ALA, ameliorated the early stages of IgAN, and these effects might be related to a reduced capacity for IL-6 production.

Effects of graded levels of Fusarium-toxin-contaminated wheat in Pekin duck diets on performance, health and metabolism of deoxynivalenol and zearalenone

1. Diets with increasing proportions of Fusarium-toxin-contaminated wheat were fed to Pekin ducks for 49 d in order to titrate the lowest effect level. Dietary deoxynivalenol (DON) and zearalenone (ZON) concentrations were successively increased up to 6 to 7 mg/kg and 0·05 to 0·06 mg/kg, respectively. 2. Feed intake, live weight gain and feed to gain ratio were not influenced by dietary treatment. 3. Gross macroscopic inspection of the upper digestive tract did not reveal any signs of irritation, inflammation or other pathological changes. The weight of the bursa of Fabricius, relative to live weight, decreased in a dose-related fashion. Activities of glutamate dehydrogenase and γ-glutamyl-transferase in serum were either unaffected or inconsistently affected by dietary treatments. 4. Concentrations of DON and of its de-epoxydised metabolite in plasma and bile were lower than the detection limits of 6 and 16 ng/ml, respectively, of the applied high performance liquid chromatography (HPLC) method. 5. ZON or its metabolites were not detectable in plasma and livers (detection limits of the HPLC method were 1, 0·5 and 5 ng/g for ZON, α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL), respectively). Concentrations of ZON, α-ZOL and β-ZOL in bile increased linearly with dietary ZON concentration. The mean proportions of ZON, α-ZOL and β-ZOL of the sum of all three metabolites were 80, 16 and 4%, respectively. 6. Taken together, it can be concluded that dietary DON and ZON concentrations up to 6 and 0·06 mg/kg, respectively, did not adversely affect performance and health of growing Pekin ducks.

Effects of graded levels of Fusarium toxin contaminated wheat in diets for fattening pigs on growth performance, nutrient digestibility, deoxynivalenol balance and clinical serum characteristics

A dose response study was carried out with pigs in order to examine the effects of increasing dietary deoxynivalenol (DON)-concentrations on performance, clinical serum characteristics, nutrient digestibility and DON-metabolism. For this purpose, wheat contaminated naturally with Fusarium toxins was incorporated into pig diets at increasing proportions to give calculated dietary DON-concentrations of 0, 2.3 and 4.6 mg/kg during the starter period of phase 1 (14 d) of the experiment, and 0/0, 1.2/1.4, 2.3/3.7 mg/kg starter/grower diet during phase 3 (56 d) of the experiment. Each diet was tested on 16 pigs of both sexes with an initial average live weight of approximately 28 kg. A recovery phase (phase 2, 21 d) was intercalated between phase 1 and 3 of the growth experiment where all groups were fed with the uncontaminated control diet since some pigs exposed to the highest dietary DON-concentration during phase 1 nearly completely refused the offered feed. Affected pigs completely recovered during this phase. In phase 3, when diets with lower DON-concentrations were fed, no differences in performance could be detected. Serum clinical characteristics (enzymes indicating liver damage, total protein, immunoglobulins) did not respond to increasing DON-concentration in the diets. DON-concentration in serum increased in a dose-response-related manner as dietary DON-concentration increased. However, this parameter was not or only weakly correlated to any of the examined performance parameters or serum characteristics. Also, nutrient digestibility of the diets and N-retention were not affected by treatments with the exception of crude fat digestibility which was not consistently influenced. Concentration of DON and its metabolite de-epoxy-DON increased in urine with increasing dietary DON-concentration in a strongly linearly related fashion. The proportion of the excretion of de-epoxy-DON of the total urinary excretion of DON plus de-epoxy-DON rose linearly up to approximately 4%. Total recovery of DON plus de-epoxy-DON as percentage of DON-intake varied between 45 and 57% and was not influenced by dietary DON-concentration. Only a very small fraction of approximately 0.1% of ingested DON was recovered in faeces.

Feed intake, growth and carcass parameters of swine consuming diets containing low levels of deoxynivalenol from naturally contaminated barley

The ubiquitous nature of deoxynivalenol (DON) in the eastern prairie region of Canada necessitates the development of strategies to enhance the utilization of affected grains by swine producers. To this end, an experiment was designed to determined the impact of low levels of DON on feed intake and growth of swine. 144 Cotswold pigs (initial weight = 23.4 kg ± 0.3 SE) were assigned to receive diets containing either 0, 1 or 2 ppm DON in the final feed (four pens, each containing six barrows and six gilts, per treatment). The final DON contents of the diets were derived by diluting DON-contaminated barley (DON = 4.9 ppm) with DON-free barley. Diets were formulated to provide a minimum of 13.4 MJ kg-1 digestible energy (DE) and 0.81% total lysine, and the same diets were used throughout the grow-finish period. Feed intake (per pen basis; kg d-1), body weight gains (kg d-1) and feed conversion were measured on a weekly basis. Pigs were slaughtered at approximately 110 kg and indices of carcass merit collected. The presence of 2 ppm DON depressed feed intake by 7.6% (P < 0.05) relative to 0 ppm DON controls, with pigs consuming the 1 ppm DON diet having intermediate levels of feed depression. However there was no significant effect of DON on average daily gain or feed conversion at any stage of the experiment, The presence of DON in the diet increased the proportion of animals reaching 110 kg, estimated from individual regression curves, at times greater than the median value (169.5 d; chi-squared analysis P < 0.05), in gilts, but was without effect on barrows (median = 158.2 d). Measures of carcass weight, index, backfat thickness, and depth of lean over the loin were not affected (P > 0.05) by the presence of DON in the diet, irrespective of gender, however there was significant linear effect of DON (P < 0.05) on the loin premiums received, with higher values realized with increasing DON content in the diet. The current data provide evidence that grains containing DON could be used in the diets of barrows to provide 2 ppm in the final feed however, caution is required when considering their utilization for gilts. Key words: Deoxynivalenol, feed intake, performance, swine, barley, carcass merit

The effect of fusarium toxin contaminated maize on performance and health of female weaning piglets

The influence of increasing amounts of zearalenone and de-oxynivalenol in diets for prepubertal pigs was investigated on 100 female piglets fed diets with increasing concentrations of ZON and DON (0.01mg ZON and 0.2mg DON/kg to 0.42mg ZON and 3.9mg DON/kg). Concentrations of 0.06mg ZON and 0.8mg DON per kg diet caused a significant decrease of serum concentrations of GLDH and FSH as well as vulva swelling. The uterus weight of the piglets receiving 0.42mg ZON and 3.9mg DON/kg was increased by almost 100% compared to the control. Furthermore, this group showed significantly decreased performance, serum protein concentration and zervix swelling. Further studies are needed to scrutinize the adverse effects of ZON and DON in diets for prepubertal female piglets, especially on future reproduction performance.

Overt signs of toxicity to dogs and cats of dietary deoxynivalenol.

Studies were conducted to determine the dietary amounts of deoxynivalenol (DON; vomitoxin) in dog and cat food that are required to produce overt signs of toxicity (e.g., vomiting or reduced food intake). Wheat naturally contaminated with 37 mg of DON/kg was used to manufacture pet foods containing 0, 1, 2, 4, 6, 8, and 10 mg of DON/kg. Deoxynivalenol concentration in pet food following manufacture was unchanged, indicating that the toxin was stable during conventional extrusion processing. Dogs previously fed DON-contaminated food were able to preferentially select uncontaminated food. Dogs not previously exposed to DON-contaminated food consumed equal quantities of contaminated and uncontaminated food. There was no effect of 6 mg of DON/kg on dog food digestibility. Food intake of dogs was significantly reduced by DON concentrations greater than 4.5 +/- 1.7 mg/kg, and DON greater than 7.7 +/- 1.1 mg/kg reduced cat food intake. Vomiting by dogs and cats was commonly observed at the 8 and 10 mg DON levels.

Effect of intraperitoneal infusion of deoxynivalenol on feed consumption and weight gain in the pig.

The mycotoxin deoxynivalenol (DON) is well documented to cause reduced feed consumption (FC) and weight gain (WG) rates in sensitive animal species. In the present study, the effect of DON on pigs when ingested as a DON-spiked diet was compared with toxin administered by a continuous-delivery osmotic pump that was implanted intraperitoneally (i.p.). The trial was conducted for a 7-day period. At 4 ppm dietary DON, overall FC and WG were reduced -14% and -8%, respectively, compared with control animals; at 9 ppm DON, values were -46% and -65% less, respectively. With i.p. infusion of te toxin, although FC was also reduced [-16% at 2 micrograms DON/hr (low dose) or -31% at 5 micrograms DON/hr (high dose)], WG rates were affected to a relatively less extent (-5% or -9%, respectively) than that noted with dietary DON. In pigs on dietary DON, both FC and WG were most affected during the initial 3-day period and showed significant recovery thereafter; however, in animals dosed by the i.p. pump, FC improved only moderately, and WG stayed relatively constant over the 7 days. The effect of dietary DON on WG appears to be influenced by more than just reduced feed intake, particularly at higher toxin concentrations.

Moniliformin from Fusarium fujikuroi Culture Material and Deoxynivalenol from Naturally Contaminated Wheat Incorporated into Diets of Broiler Chicks

The effects of feeding diets containing 100 mg moniliformin (M)/kg of feed from culture material and 16 mg deoxynivalenol (DON)/kg of feed from naturally contaminated wheat were evaluated in growing broiler chicks from 1 day to 21 days of age. Body weight (BW), body-weight gain, and feed consumption were decreased by feeding M and M plus DON diets. Relative heart weight was increased by the M diet, whereas relative weights of proventriculus, gizzard, and heart were increased by the M plus DON diet. The M diet increased alanine transferase and aspartate transaminase activities and creatinine concentration and decreased mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration (MCHC). The M and DON diet decreased glucose, hemoglobin, and MCHC. Histopathological lesions from the M diet were limited to the kidney and consisted of extensive renal tubular epithelial degeneration plus luminal mineralization. A moderation of the severity of lesions was seen in the tissues of the M plus DON-fed chicks, consisting of generally mild tubular epithelial degeneration. None of the parameters measured were affected by the DON diet. Results indicate additive or less-than-additive toxicity for most parameters when chicks were fed diets containing 100 mg M plus 16 mg DON/kg of feed. Although the concentration of M in this study was high compared with that reported for feedstuffs, additional information on the occurrence and toxicity of M will need to be collected in order to assess the importance of M to the poultry industry.

Effect of feeding blends of Fusarium mycotoxin-contaminated grains containing deoxynivalenol and fusaric acid on growth and feed consumption of immature swine.

Experiments were conducted to determine the effect of feeding diets containing combinations of the Fusarium metabolites deoxynivalenol (DON) and fusaric acid (FA) to starter swine. In all experiments, pigs of approximately 8.2 kg initial weight were fed diets containing blends of mycotoxin-contaminated corn, wheat, and barley for 21 d with growth and feed consumption determined weekly. In the first experiment, diets were determined to contain 0 microgram DON/g + 58.9 micrograms FA/g (control), 4.4 micrograms DON/g + 57.1 micrograms FA/g, 6.0 micrograms DON/g + 48.6 micrograms FA/g, and 7.5 micrograms DON/g + 57.4 micrograms FA/g. The feeding of all diets containing DON caused significant linear depressions in growth and feed intake after only 1 wk. Lower concentrations of DON and FA were fed in the second experiment with diets containing 0 microgram DON/g + 16.3 micrograms FA/g (control), .5 microgram DON/g + 14.3 micrograms FA/g, 1.1 micrograms DON/g + 14.1 micrograms FA/g, and 1.9 micrograms DON/g + 13.6 micrograms FA/g. There was a significant linear reduction in feed intake after 1 wk with increasing levels of dietary DON. Weight gains declined significantly only after 3 wk. Increasing amounts of FA combined with relatively constant amounts of DON were fed in the third experiment. By analysis, diets contained .5 micrograms DON/g + 2.9 micrograms FA/g (control), 2.2 micrograms DON/g + 12.2 micrograms FA/g, 2.5 micrograms DON/g + 15.6 micrograms FA/g, and 2.4 micrograms DON/g + 15.9 micrograms FA/g. In the 1st wk, the feeding of increasing amounts of fusaric acid combined with a relatively constant amount of DON caused a significant linear depression in weight gain. We concluded that a toxicological synergism exists between DON and FA when fed to immature swine and that FA concentrations in feeds should be determined whenever DON analysis is conducted.

Effects of feeding diets containing Fusarium (naturally) contaminated wheat or pure deoxynivalenol (DON) in growing pigs

Three experiments were conducted to determine the effects of feeding diets containing laboratory synthesized deoxynivalenol (DON), or Fusarium (naturally) contaminated wheat containing DON on performance and health of young pigs (32.8–41.1 kg body weight). Diets containing 3.4–19.1 mg DON kg−1 were fed to pigs ad libitum for 14 d (exps. 1 and 2) or 7 wk (exp. 3) after which time each pig was slaughtered and blood, tissue and organ samples taken for analysis. All pigs responded to DON-contaminated diets with an immediate reduction in feed intake and body weight gain followed by some degree of recovery that was dependent on the dietary DON concentration. Negative linear relationships were found between feed intake or body weight gain and dietary DON concentration with pure DON and naturally contaminated wheat diets. Feed intake and weight gain were, respectively, 18 and 23% lower when a diet containing naturally contaminated wheat was fed compared to a diet containing an equivalent concentration of pure DON. Effects of DON on organ weights, relative to body weight, were inconsistent among experiments. The gastric mucosa was thinner and more eroded and had a higher degree of folding in the esophageal region in most groups fed DON-contaminated diets compared to those fed the control diet. Effects of DON on the fundic and cardiac regions of the stomach were inconsistent among treatments and experiments. There was little or no effect of DON on most of the blood parameters measured. Key words: Pure deoxynivalenol, naturally contaminated wheat, swine, intake, gain, vomitoxin, mycotoxin, fusarium, trichothecene

Effects of low-level dietary deoxynivalenol on haematological and clinical parameters of the pig.

The subacute toxic effects of dietary deoxynivalenol (DON) were examined in grower pigs during a 32 day feeding period. DON was incorporated into the feed at 0, 1, and 3 mg/kg, added as either the purified toxin (P) or as naturally contaminated corn (N). Growth performance and blood biochemical and haematological parameters were monitored throughout the study. At the higher toxin levels (diets 3P, 3N) significantly lower feed consumption and body weight gains were evident soon after the start of feeding, but while weight gains of pigs fed the pure DON diet (3P) recovered after several days, values for pigs fed the naturally contaminated diet (3N) remained depressed over the course of the study. It is possible that these observations reflected the presence of other unidentified toxic compounds in the naturally contaminated grain. Generally, blood chemistry parameters of pigs fed the contaminated diets were not different from controls, with the exception of alpha-globulin and possibly cortisol in animals receiving diets 3N or 3P. Data suggested that the effect of DON on the alpha-globulin fraction may have been independent of the feed refusal syndrome associated with this toxin. Alterations in several haematological measurements were noted to occur sporadically with the 3 ppm diets, including higher RBC count, haematocrit and platelet level, however these effects could not be separated from the influence of decreased feed intake and were of limited value in diagnosing the effects of low level dietary DON on swine.

The effects of naturally deoxynivalenol-contaminated oats on the clinical condition, blood parameters, performance and carcass composition of growing pigs.

A feeding trial with naturally deoxynivalenol (DON)-contaminated oats included in feed mixtures at graded levels was conducted in growing pigs. The DON concentrations were 0, 0.7, 1.7, and 3.5 mg/kg of complete feed mixture given ad libitum to different groups. The data recorded were feed consumption, body weight gain, slaughter weight, biochemical and haematological data including serum immunoglobulin A, clinical condition and post-mortem pathology including histopathology. Significantly decreasing body weight gain throughout the experimental period, decreased slaughter weight and reduced feed utilization efficiency were observed for the group fed a diet containing 3.5 mg/kg of DON. At the same DON concentration, there were increased liver weights and decreased concentrations of serum protein and albumin, and a temporary fall in packed blood cell volume, serum calcium and serum phosphorus. For the groups fed diets containing 1.7 and 3.5 mg/kg of DON, a statistically significant, dose-related decrease in daily feed consumption was observed. No other effects on haematological, biochemical or immunological parameters were recorded. The carcass quality was not affected in any group. It was concluded that significant effects in growing pigs may be observed at a dietary DON concentration of 1.7 mg/kg, originating from naturally contaminated oats included in a diet that was otherwise adequate and contained only minor traces of other mycotoxins.

Influence of subchronic exposure to low dietary deoxynivalenol, a trichothecene mycotoxin, on intestinal absorption of nutrients in mice

during a 6-wk feeding trial, effects of low dietary deoxynivalenol (DON; 0, 0.1, 1 and 10 ppm) on food consumption and weight gain were investigated in male mice. Food intake was similar in all four dietary groups. Weight gain in the group receiving 10 ppm DON was significantly ( P < 0.01) reduced. At the end of the feeding period, test animals were sacrificed and absorption of water, d-glucose, l-leucine, l-tryptophan, 5-methyltetrahydrofolic acid and iron was measured in isolated perfused jejunal segments in vitro. No effects were observed on absorption of water, leucine, tryptophan and iron. However, at a dietary DON concentration of 10 ppm, a slightly but significantly ( P < 0.05) reduced transfer of glucose was measured. Furthermore, transfer as well as tissue accumulation of 5-methyltetrahydrofolic acid in the jejunal segment were both significantly decreased up to 50%. Heavy metal and trace element content was determined in liver, kidney and small intestine. Manganese and molybdenum content in liver tissue was reduced with a DON concentration of 10 ppm in the diet. The findings indicate that subchronic ingestion of DON, in concentrations occurring in contaminated food and feed, results in an impairment of intestinal transfer and uptake of nutrients such as glucose and 5-methyltetrahydrofolic acid.

Effects of Feeding Deoxynivalenol (DON, Vomitoxin)-Contaminated Wheat to Female White Leghorn Chickens from Day Old Through Egg Production

White Leghorn chickens one day of age were fed starter and grower diets containing either a control (noncontaminated) wheat diet or a naturally contaminated deoxynivalenol (DON) wheat diet (18 mg DON/kg) from 1 day of age to the onset of egg production. The hens were then placed on their respective layer diets of control wheat or DON-contaminated wheat (18 mg DON/kg) for six 28-day egg production periods. Feeding the DON-contaminated diet did not significantly influence body weights during the growing or the laying phases. Overall, hen-day egg production and egg weights were significantly higher for hens receiving the DON diet. Feeding DON contaminated wheat caused no significant changes in percent shell, albumen height, percent fertility, percent hatch of fertile eggs, percent hatch of eggs set, or weight of chicks at hatch. There were slight, although significant, changes in shell weight and shell thickness and in some serum chemistry values. There were no significant differences in the hematology parameters measured or in prothrombin times. None of the eggs collected from hens fed the control and the DON-contaminated wheat diet contained detectable quantities of DON. Microscopic examination of sections of the liver, kidney, and proventriculus of control and treated hens revealed no unusual histopathology. The results indicate that feeding DON at relatively high levels beginning at 1 day of age and continuing through six egg production periods had only slight effects on the parameters measured.

Suppression of immune response in the B6C3F 1 mouse after dietary exposure to the fusarium mycotoxins deoxynivalenol (vomitoxin) and zearalenone

The effect that dietary exposure to the naturally-occurring Fusarium graminearum toxins deoxynivalenol (DON) and zearalenone (ZEA) may have on immune function was assessed in the B6C3F 1 mouse. Dietary DON depressed the plaque-forming response to sheep red blood cells, the delayed hypersensitivity response to keyhole limpet haemocyanin and the ability to resist Listeria monocytogenes. Listerial resistance was similarly decreased in control mice fed restricted diets comparable to the dietary restriction caused by DON-induced feed refusal, whereas equivalent food restriction did not decrease the plaque or delayed hypersensitivity responses. ZEA ingestion decreased resistance to L. monocytogenes but did not affect splenic plaque-forming or delayed hypersensitivity responses. Resistance to Listeria was reduced to a greater extent by co-administration of DON and ZEA than by DON alone, whereas the ability of DON to inhibit the delayed hypersensitivity response was significantly lessened in the presence of ZEA. While effects on resistance to Listeria and delayed hypersensitivity were detectable in mice ingesting the mycotoxins for 2–3 wk, these effects disappeared upon extension of the feeding period to 8 wk. In contrast, some effect on the plaque-forming response was detectable with both the 2- and the 8-wk period of mycotoxin ingestion. Immunosuppression can thus result from ingestion of F. graminearum-infected agricultural staples, the suppression being attributable to interactions between direct immunotoxic effects of DON and ZEA and nutritional effects associated with DON-induced food refusal.

Effects of 8-week exposure of the B6C3F1 mouse to dietary deoxynivalenol (vomitoxin) and zearalenone

Weanling female B6C3F1 mice were fed semi-purified diets containing 0, 0.5, 2.0, 5.0, 10.0 or 25.0 ppm (mg/kg) deoxynivalenol (DON) over 8 wk and were assessed for effects on feed intake, body-weight gain, terminal organ weights, histopathology, haematology and serum immunoglobulin levels. To determine whether DON effects were potentiated by the oestrogen zearalenone (ZEA), a mycotoxin frequently found to occur with DON in cereals, two additional groups of mice were fed diets containing either 10 ppm ZEA or 10 ppm ZEA plus 5 ppm DON. The rate of body-weight gain was significantly reduced ( P < 0.01) for all mice consuming feed containing 2.0 ppm or more of DON, whereas only the mice ingesting the diet containing 25 ppm DON showed a significantly decreased ( P < 0.01) rate of feed consumption. Gross and histopathological evaluation of thymus, spleen, liver, kidney, uterus, small intestine, colon, heart, brain, lungs and bone marrow from control and all mycotoxin-exposed mice revealed that these tissues were normal in appearance and in histological architecture. DON-amended diets did however, cause dose-dependent decreases in the terminal organ weights recorded (thymus, spleen, liver, kidney and brain). In the DON-treated groups, statistically significant dose-dependent decreases in the counts of total circulating white blood cells were associated with an increase in polymorphonuclear neutrophils and a decrease in lymphocytes and monocytes. Dietary DON caused a dose-dependent decrease in serum IgM but, in contrast, a dose-dependent increase in serum IgA. In none of the above instances was 10 ppm ZEA shown to act synergistically or antagonistically with 5 ppm DON. Since dietary DON at levels as low as 2.0 ppm exerted significant effects on the growing B6C3F1 female mouse, future approaches should include studies of the mechanisms by which this mycotoxin affects nutrient utilization and modifies the normal immune response.

Effects of Feeding White Leghorn Hens Diets that Contain Deoxynivalenol (Vomitoxin)-Contaminated Wheat

A short-term (10 weeks, Experiment 1) and a long-term experiment (24 weeks, Experiment 2) were done to determine effects of incorporating either white winter wheat, naturally contaminated with 1 mg deoxynivalenol (DON)/kg, or spring wheats, containing up to 6.5 mg DON/kg, into the diets of White Leghorn hens. Based on chemical analysis, the diets in Experiment 1 contained <.05 to .7 mg DON/kg, while those in Experiment 2 contained from .2 to 4.9 mg/kg. Incorporation of winter or spring wheat in the experimental diets had no effect (P>.05) on feed intake and efficiency, egg production and yield, the number of soft shell and cracked eggs observed in the laying house, body weight at the completion of the experimental period, fertility, hatchability of fertile eggs, and the proportion of malformed embryos and pips. In addition, presence of DON-contaminated wheat did not influence (P>.05) the organ weight to body weight ratio for a randomly selected sample of hens necropsied at the completion of each experiment. There was little evidence of lesions in the oral cavity, esophagus, proventriculus and gizzard, hemorrhaging in the viscera or skeletal muscles, or of changes in the appearance of spleen, heart, and kidney. However, the livers from DON hens were fatty in appearance. Furthermore, vomiting (emesis), diarrhea, or changes in behaviour were not apparent and mortality, normally very low, was not increased during either experiment. Inverse linear relationships were obtained in Experiment 1 between dietary DON concentrations and egg weight (P<.05), shell weight and thickness (P<.01), and percent shell (P<.05). Although egg and shell variables measured in Experiment 2 were not significantly influenced (P>.05) by DON treatment, trends towards lower values with higher dietary DON levels were evident. Egg specific gravity, nondestructive deformation, and quasistatic compression fracture strength of the egg's shell were not influenced (P>.05) by dietary DON levels. The results from these experiments indicate that laying hens can tolerate diets containing up to 5 mg DON/kg from white winter or spring wheat for extended periods of time without serious adverse effects on health and productivity.