Effect of Sub-Clinical Mycotoxin Exposure on Growth Performance and Immune Response in Eimeria-Challenged Pullets

    

An experiment was conducted to investigate the effects of subclinical mycotoxin exposure on the growth performance and immune cell dynamics in pullets exposed to coccidiosis. Using a 2x2 factorial design, a total of 288 four-week-old Hy-Line W36 pullets were randomly allocated to four treatment groups, each containing six replicated cages with 12 birds. The experimental groups were exposed to either non-contaminated or mycotoxin-contaminated diets and subjected to either a non-challenge or a challenge with Eimeria spp. Mycotoxin-exposed group was fed a diet with naturally contaminated corn distillers dried grains with solubles included at the level of 20% in the feed, providing an average of 1.3 mg deoxynivalenol, 56 µg zearalenone, and 0.06 mg fumonisins per kg of feed. Eimeria-challenged group was orally inoculated with sporulated oocysts of 50,000 E. acervulina, 10,000 E. maxima, and 10,000 E. tenella per dose on the second week of the experiment. Growth performance, intestinal permeability, intestinal lesions, and immune cell dynamics were measured at 6 and 14 days Eimeria post-inoculation (DPI). Data were subjected to two-way ANOVA for the main and interaction effects, and the significance level was set at 0.05. Eimeria infection significantly reduced feed intake (FI) by 23% and body weight (BW) by 14% from 1 to 6 DPI, while increasing the intestinal permeability at 5 DPI, intestinal lesions, and the ratio of CD4+ to CD8+ T cells in the cecal tonsils at 6 DPI (P < 0.05). Mycotoxin exposure further decreased the FI by 3.8% and BW by 1%, increasing the intestinal lesions and the CD4+:CD8+ T cells (P < 0.05). From 7 DPI, FI started to recover in the Eimeria-challenged group and completely recovered in 14 DPI. However, recovery was less effective with mycotoxin exposure. At 14 DPI, the CD4+ to CD8+ T cell ratios were similar in the non-challenged and Eimeria-challenged group. However, the pullets exposed to mycotoxins had a higher CD4+ to CD8+ ratio, which was further increased with Eimeria infection. It can be concluded that the presence of mycotoxins in the feed can negatively affect the growth performance and impair the recovery of the pullets infected with coccidiosis.

Key Words: Subclinical mycotoxin exposure, Growth performance, Immune response, Pullets, Coccidiosis.