Assessment of the Impact of Humic Acids on Intestinal Microbiota, Gut Integrity, Ileum Morphometry, and Cellular Immunity of Turkey Poults Fed an Aflatoxin B₁-Contaminated Diet

A recent study published data on the growth performance, relative weights of the organs of the gastrointestinal tract, liver histology, serum biochemistry, and hematological parameters for turkey poults fed an experimental diet contaminated with aflatoxin B-1 (AFB(1)) and humic acids (HA) extracted from vermicompost. The negative effects of AFB(1) (250 ng AFB(1)/g of feed) were significantly reduced by HA supplementation (0.25% w/w), suggesting that HA might be utilized to ameliorate the negative impact of AFB(1) from contaminated diets. The present study shows the results of the remaining variables, as an extension of a previously published work which aimed to evaluate the impact of HA on the intestinal microbiota, gut integrity, ileum morphometry, and cellular immunity of turkey poults fed an AFB(1)-contaminated diet. For this objective, five equal groups of 1-day-old female Nicholas-700 turkey poults were randomly assigned to the following treatments: negative control (basal diet), positive control (basal diet + 250 ng AFB(1)/g), HA (basal diet + 0.25% HA), HA + AFB(1) (basal diet + 0.25% HA + 250 ng AFB(1)/g), and Zeolite (basal diet + 0.25% zeolite + 250 ng AFB(1)/g). In the experiment, seven replicates of ten poults each were used per treatment (n = 70). In general, HA supplementation with or without the presence of AFB(1) showed a significant increase (p < 0.05) in the number of beneficial butyric acid producers, ileum villi height, and ileum total area, and a significant reduction in serum levels of fluorescein isothiocyanate-dextran (FITC-d), a marker of intestinal integrity. In contrast, poults fed with AFB(1) showed a significant increase in Proteobacteria and lower numbers of beneficial bacteria, clearly suggesting gut dysbacteriosis. Moreover, poults supplemented with AFB(1) displayed the lowest morphometric parameters and the highest intestinal permeability. Furthermore, poults in the negative and positive control treatments had the lowest cutaneous basophil hypersensitivity response. These findings suggest that HA supplementation enhanced intestinal integrity (shape and permeability), cellular immune response, and healthier gut microbiota composition, even in the presence of dietary exposure to AFB(1). These results complement those of the previously published study, suggesting that HA may be a viable dietary intervention to improve gut health and immunity in turkey poults during aflatoxicosis.