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Publication type: PhD Thesis

Year: 2007

Author(s): Awad, W

Title: Effects of the fusarium toxin deoxynivalenol (DON) on digestive functions of chickens.

Source: PhD-Arbeit, Vet. Med. Univ. Wien, pp. 87.

Authors Vetmeduni Vienna:

Awad Wageha

Advisor(s):
Zentek J├╝rgen


Abstract:
The aim of the present studies was to evaluate the effects of deoxynivalenol (DON) on feed intake, performance, organ weights, intestinal histology, electrophysiological parameters of the gut, intestinal glucose uptake, and absorption of DON itself in chickens┬┐ jejunum, and to investigate the efficacy of a probiotic feed additive (Eubacterium sp., PB) with the ability to deepoxidize DON. DON had no effects on zootechnical traits. Body weight development and feed utilization were not adversely affected by the inclusion of of 10 mg/kg of DON in the diets. A slight improvement in feed intake and body weight gain over the course of the experiment was observed in broilers fed DON-PB. The absolute or relative organ weights were not altered in broilers fed the diet containing DON compared with controls and DON-PB group, moreover, the relative liver weight was slightly decreased in broilers fed the diet containing DON. DON altered small intestinal morphology, especially in the duodenum and jejunum, as evidenced by shorter and thinner villi. Functional effects of DON were determined in jejunal tissue in Ussing chambers. Short ciruit current (Isc) was decreased by DON when D-glucose and proline were added to jejunal tissue. It was suggested that DON impaired the Na+-D-glucose co-transport (SGLT1) for DON decreased glucose uptake almost as efficiently as phlorizin, a specific inhibitor of SGLT1. The similarity between the effects of phlorizin and DON on glucose uptake evidences their common ability to inhibit Na+-D-glucose co-transport. Deoxynivalenol (DON) decreased glucose absorption in the chicken small intestine after dietary exposure and also by direct in vitro addition. The observation that DON decreased the Isc after addition of proline indicates that DON inhibited the Na+-amino acid co-transport and leads to the assumption that the inhibition of Na+ co-transport systems is an important mechanism for DON toxicity in chickens. DON was absorbed from the jejunum related to the concentration when added to the mucosal epithelial side. The predominant part of the DON passes across the chicken intestinal epithelium by passive diffusion, likely via the paracellular pathway. The results imply that the exposure to DON contaminated feeds may negatively affect animal health and performance by local (i.e. inhibition of intestinal SGLT1) and systemic effects. The addition of Eubacterium sp. (DSM 11798) as probiotic was effective in counteracting the electrophysiological alterations caused by DON in the gut tissue. As well it was effective to alleviate the histological alterations and maintanined a comparable villus length as in the control group. It can be concluded that diets with DON contamination below levels that induce negative impact on health and performance in chicken could affect small intestinal morphology and intestinal absorptive capacity. Further research should be directed towards the toxic mechanisms by molecular, proteomic and metabolomic tools as well as towards the impact on the local and general immune function.

Keywords:
Deoxynivalenol / digestive functions / chickens


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