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Research Project: Reducing Animal Stress and the Incidence or Prevalence of Human Pathogens through Enhanced Gastrointestinal Microbial and Immune Functions in Farm Animals

Location: Livestock Behavior Research

Title: Susceptibility of broiler chickens to coccidiosis when fed subclinical doses of deoxynivalenol and fumonisins – special emphasis on the immunological response and the mycotoxin interaction

Author
item Grenier, B - Purdue University
item Dohnal, I - Biomin Research Center
item Shanmugasundaram, R - Ohio Agricultural Research & Development Center
item Eicher, Susan
item Selvaraj, R - Ohio Agricultural Research & Development Center
item Schatzmayr, G - Biomin Research Center
item Applegate, T - Purdue University

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2016
Publication Date: 7/27/2016
Citation: Grenier, B., Dohnal, I., Shanmugasundaram, R., Eicher, S.D., Selvaraj, R.K., Schatzmayr, G., Applegate, T.J. 2016. Susceptibility of broiler chickens to coccidiosis when fed subclinical doses of deoxynivalenol and fumonisins – special emphasis on the immunological response and the mycotoxin interaction. Toxins. 8(8):231. doi: 10.3390/toxins8080231.

Interpretive Summary: Mycotoxins in animal feeds have been shown to be detrimental for many livestock species. In this study, we demonstrated that mycotoxins caused intestinal damage and decreased availability of some nutrients, but did not reduced growth in chickens given feeds with mycotoxins and challenged with coccidia (a frequent pathogen for chickens). A section of the small intestine (jejunum) had higher expression of the immune communication molecules(cytokines) following the infection for birds given the mycotoxins. More cells that suppress the immune responses, regulatory T-cells, were found in the immune organs (cecal consils) and were associated with the greater immune response. These data point to the necessity of attending to toxin levels in feeds for chickens. The toxins may not alter growth, but increase susceptibility when a pathogen challenge is present.

Technical Abstract: Deoxynivalenol (DON) and fumonisins (FB) are the most frequently encountered mycotoxins produced by Fusarium species in livestock diets. The effect of subclinical doses of mycotoxins in chickens is largely unknown, and in particular the susceptibility of birds to pathogenic challenge when fed these fungal metabolites. Therefore, the present study reports the effects of DON and FB on chickens challenged with Eimeria spp, responsible for coccidiosis. Broilers were fed diets from hatch to 20 d, containing no mycotoxins, 1.5 mg DON/kg, 20 mg FB/kg, or both toxins (12 pens/diet; 7 birds/pen). At 14 d, 6 pens of birds per diet (half of the birds) were challenged with a 25X-recommended dose of coccidial vaccine, and all birds (challenged and unchallenged) were sampled 6 d later. As expected, performance of birds was strongly affected by the coccidial challenge. Ingestion of mycotoxins did not further affect the growth but repartitioned the rate of reduction (between the fraction due to the change in maintenance and feed efficiency), and reduced (P < 0.05) apparent nitrogen digestibility. Intestinal lesions and number of oocysts in the jejunal mucosa and feces of challenged birds were more frequent and intense (P < 0.05) in the birds fed mycotoxins than in birds fed control feed. The upregulation of cytokines following coccidial infection was higher (P < 0.05) in the jejunum of birds fed mycotoxins (IL-1ß, IL-6, IL-8 and IL-10). Further, the higher intestinal immune response was associated with a higher (P < 0.05) percentage of lymphocytes T CD4+CD25+, also called Tregs, observed in the cecal tonsils of challenged birds fed mycotoxins. Interestingly, the increase (P < 0.05) in FB biomarker of exposure (sphinganine/sphingosine ratio in serum and liver) suggested a higher absorption and bioavailability of FB in challenged birds. The interaction of DON and FB was very dependent on the endpoint assessed, with three endpoints reporting antagonism, nine additivity, and two synergism. In conclusion, subclinical doses of DON and FB showed little effects in unchallenged chickens, but seem to result in metabolic and immunologic disturbances that amplify the severity of coccidiosis. Therefore, attending to toxin levels is imperative to maintaining immune competence of chickens.