Immunomodulatory effects of Fusarium mycotoxins in broiler breeder pullets infected with Coccidia
Fusarium' mycotoxins are low molecular weight fungal metabolites which are frequently encountered in grains used for poultry feeds, Among these mycotoxins, deoxynivalenol (DON), acetylated DON derivatives and zearalenone (ZEN) are the most commonly detected 'Fusarium' mycotoxins in Canadian-grown feedstuffs. There is a lack of information regarding the effects of 'Fusarium' mycotoxicoses on broiler breeder pullets especially when the birds get infected with pathogens. Experiments were conducted to study the effects of feeding diets naturally contaminated with 'Fusarium' mycotoxins on broiler breeder pullets infected with coccidia, with special emphasis on immune parameters. Coccidiosis is a common disease in the poultry field against which broiler breeder chicks are usually vaccinated in the hatchery or during the first few days of life. The contaminated diets were formulated by replacing corn and wheat of the control diets with those naturally contaminated with 'Fusarium' mycotoxins. It was found that feeding diets naturally contaminated with ' Fusarium' mycotoxins had no effects on immune parameters in the absence of infection. Immunomodulation was observed, however, upon primary and secondary infection with single or multiple coccidia species. Such immunomodulation involved the systemic parameters of total serum immunoglobulin (Ig) concentrations and blood lymphocyte subsets as well as local intestinal parameters such as recruited immune cell subsets and immune-related gene expression. Morphometry of villus-crypt units in the intestinal tract provided evidence of the occurrence of compensatory changes that explained the lack of 'Fusarium' mycotoxins effects on body weight gain in experimental birds. 'Fusarium ' mycotoxins also impaired the recovery of intestinal villi following coccidial challenge. Apart from its mycotoxin binding capacity, a glucomannan mycotoxin adsorbent (GMA) derived from yeast cell wall had immunomodulatory effects on its own. It was concluded that feeding grains containing ' Fusarium' mycotoxins, below levels that affect growth performance, to broiler breeder pullets could modulate immune response to coccidiosis and alter intestinal morphology. It is recommended that the feeding of grains naturally contaminated with 'Fusarium' mycotoxins to broiler breeder pullets should, therefore, be minimized.