Effects of Yeast Cell Wall Supplementation in Broiler Chickens Under Dietary Aflatoxin Challenge

Aflatoxins (AFLAs) are highly prevalent mycotoxins in poultry production and are known to impair immune function and may reduce vaccine responsiveness. Therefore, this study evaluated whether dietary supplementation with yeast cell wall (YCW) could modulate the immune response under AFLA challenge and support vaccine response in broilers. A total of 144 one-day-old chicks were distributed into four treatments: negative control (NC), AFLA-contaminated diet (2.5 ppm), YCW (500 g/t), and YCW + AFLA. Birds were vaccinated against Newcastle Disease Virus (NDV) on D14. Body weight, hepatic pathology, intestinal permeability, circulating immune cell populations, phagocytic activity, and NDV-specific antibody titers were evaluated throughout the experimental period. AFLA exposure induced significant hepatic lesions and reduced body weight on D35 but did not alter the systemic immune parameters or intestinal permeability. Liver lesions were not prevented by the use of YCW, but body weight was positively correlated to the YCW intervention. Interestingly, YCW supplementation modulated immune responses in a context-dependent manner. In birds not exposed to AFLA, YCW increased anti-NDV antibody titers following vaccination. Contrarily, under AFLA challenge (and only in this situation), YCW supplementation was associated with changes in circulating immune cell populations and increased monocyte phagocytic activity, but in the presence of AFLA, YCW did not associate with increased anti-NDV titers. These findings indicate that YCW uniquely modulates selected innate and adaptive immune responses in broiler chickens exposed to AFLA, which is an important biological interaction with relevance to feed formulation for animal production.