Susceptibility of Broiler Chickens to Coccidiosis When Fed Subclinical Doses of Deoxynivalenol and Fumonisins—Special Emphasis on the Immunological Response and the Mycotoxin Interaction

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 day 20, containing no mycotoxins, 1.5 mg DON/kg, 20 mg FB/kg, or both toxins (12 pens/diet; 7 birds/pen). At day 14, six pens of birds per diet (half of the birds) were challenged with a 25×-recommended dose of coccidial vaccine, and all birds (challenged and unchallenged) were sampled 6 days 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 apparent nitrogen digestibility. Intestinal lesions and number of oocysts in the jejunal mucosa and feces of challenged birds were more frequent and intense in the birds fed mycotoxins than in birds fed control feed. The upregulation of cytokines (interleukin (IL) IL-1β, IL-6, IL-8 and IL-10) following coccidial infection was higher in the jejunum of birds fed mycotoxins. Further, the higher intestinal immune response was associated with a higher percentage of T lymphocytes CD4+CD25+, also called Tregs, observed in the cecal tonsils of challenged birds fed mycotoxins. Interestingly, the increase 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.

Enzymatic hydrolysis of fumonisins in the gastrointestinal tract of broiler chickens

“…Nonetheless, the very poor absorption of FB (less than 5%) implies that a substantial part of FB remains in the gastrointestinal tract ( GIT ), and therefore intestinal epithelial cells are exposed to high FB concentrations. In agreement with that, new evidence has emerged that broiler chickens fed with 10 to 20 mg FB/kg of feed (EU and US guidance levels set at 20 and 50 mg/kg, respectively) were more susceptible to necrotic enteritis and coccidiosis (Antonissen et al., 2015a ; Grenier et al., 2016 ), and underwent digestive and immune disturbances (Antonissen et al., 2015a ; Grenier et al., 2015 ).…”

“…Poultry have been long considered very resistant to FB, with concentrations up to 75 to 100 mg/kg not affecting performance in chickens (Ledoux et al., 1992 ; Henry et al., 2000 ; Broomhead et al., 2002 ), which is in accordance with our results on bird performance. However, the effect of FB in the GIT of chickens had never been investigated until very recently (Rauber et al., 2012 ; Antonissen et al., 2015a ; Antonissen et al., 2015b ; Grenier et al., 2015 ; Grenier et al., 2016 ). The present study shows that even at a dose as low as 10 mg FB/kg, the mucosal immunity of the jejunum might be affected.…”

Low Doses of Mycotoxin Mixtures below EU Regulatory Limits Can Negatively Affect the Performance of Broiler Chickens: A Longitudinal Study

“…Exposure of birds to mixture of DON and FB1 at levels below EU guidance limits did not affect the performance of birds raised in healthy conditions. However, under conditions of pathogenic challenge, both mycotoxins altered the response of chickens to coccidiosis [55]. Conversely, chicken fed partially purified fungal extract containing DON, ZEN and FBs alone or combined, at levels equal to the EU guidance limits, did not show any significant changes in terms of performance and organ damage, when compared with birds fed uncontaminated diets [56].…”

Fumonisin B1, B2 and B3 in Muscle and Liver of Broiler Chickens and Turkey Poults Fed with Diets Containing Fusariotoxins at the EU Maximum Tolerable Level

“…Also, as multiple contamination by toxins produced by Fusarium is common in poultry diets, and some fusariotoxins are known to change xenobiotic and nutriment absorption, concomitant exposure to several toxins could change the level of FB in tissues [10,15]. Specifically, deoxynivalenol (DON) is known to affect the intestinal barrier function in several animal species, which could modify the bioavailability of xenobiotics [16,17,18,19,20,21,22]. However, chronic exposure to DON appeared to have no influence on the oral bioavailability of a single dose of FB1 [23].…”